Partial Oxidation of Filter Cake Particles from Biomass Gasification Process in the Simulated Product Gas Environment Energy Fuels (IF 3.091) Pub Date : 2018-01-16 Jun-fei Jiang, Lin Lang, Le-teng Lin, Hua-cai Liu, Xiu-li Yin, Chuang-zhi Wu
Filtration failure occurs when filter media are blocked by accumulated solid particles. Suitable operating conditions were investigated for cake cleaning by partial oxidation of filter-cake particles (FCPs) during biomass gasification. The mechanism of the FCP partial oxidation was investigated in a ceramic filter and by using thermogravimetric analysis through a temperature-programmed route in a 2 vol % O2–N2 environment. Partial oxidation of the FCPs in the simulated product gas environment was examined at 300–600 °C in a ceramic filter that was set and heated in a laboratory-scale fixed reactor. Four reaction stages, namely, drying, preoxidation, complex oxidation, and nonoxidation, occurred in the FCP partial oxidation when the temperature increased from 30 to 800 °C in a 2 vol % O2–N2 environment. Partial oxidation was more effective for FCP mass loss from 275 to 725 °C. Experimental results obtained in a ceramic filter indicated that the best operating temperature and FCP loading occurred at 400 °C and 1.59 g/cm2, respectively. The FCPs were characterized before and after partial oxidation by Fourier-transform infrared spectroscopy, scanning electron microscopy, and Brunaeur–Emmett–Teller analysis. Fourier-transform infrared spectroscopy analysis revealed that partial oxidation of the FCPs can result in a significant decrease in C–Hn (alkyl and aromatic) groups and an increase in C═O (carboxylic acids) groups. The scanning electron microscopy and Brunaeur–Emmett–Teller analyses suggest that, during partial oxidation, the FCPs underwent pore or pit formation, expansion, amalgamation, and destruction.
Pyrolysis Kinetics of Heavy Oil Asphaltenes under Steam Atmosphere at Different Pressures Energy Fuels (IF 3.091) Pub Date : 2018-01-16 Alexandra Boytsova, Natalia Kondrasheva, Jorge Ancheyta
Thermogravimetric analysis was used to study the pressure effect on the activation energy during asphaltene gasification. The experiments were carried out under steam atmosphere at different pressures (1–80 bar) and temperatures (100–900 °C). The measured values of the total mass loss of asphaltenes are pressure dependent. They increase with rising pressure. Kinetic parameters were determined using a first-order kinetic model and integral method with thermogravimetric analysis data. The activation energy was found to vary from 189.6 to 130.4 kJ/mol and frequency factor from 4.1 × 1010 to 1.2 × 106 min–1. A decrease of both parameters was observed with an increasing pressure. Coke produced during the gasification is obviously characterized by the bigger pore size and weaker mechanical strength as the pressure increases from 1 to 80 bar. The structure of the produced coke becomes more crumbly with raising pressure. The formation of spherical carbon particles with a radius of around 5 μm was observed at high pressure (20–80 bar). The elemental composition of these particles is roughly equal: C (∼97%), S (∼2%), and O (∼1%).
Characteristics of Methane (CH4) Diffusion in Coal and Its Influencing Factors in the Qinshui and Ordos Basins Energy Fuels (IF 3.091) Pub Date : 2018-01-16 Junlong Zhao, Dazhen Tang, Yong Qin, Hao Xu, Yulong Liu, Haiyong Wu
Diffusion coefficient is usually used to evaluate the methane (CH4) diffusion properties in the coal matrix and is vital to coalbed methane (CBM) development. Although extensive literature on the CH4 diffusion coefficient can be obtained, most of them aim at the whole coal or coal rank instead of the macrolithotype. Additionally, the primary structure of coal was destroyed with the common determination technologies (e.g., the particle, steady-state, and inverse diffusion methods) which could result in great errors. In this work, to avoid the shortcomings of the above methods, nine flake coal samples from six coal mines in the Qinshui and Ordos Basins were prepared to determine the CH4 diffusion coefficient with the slab calculation model. Meanwhile, the effects on the diffusion from the gas pressure, temperature, water saturability, and coal pore structure, and the gas adsorption capacity controlled by the coal rank and macrolithotype, were analyzed to reveal the diffusion mechanism (mode) at the CBM reservoir and laboratory conditions. Results show that the CH4 diffusion coefficient, at an order of magnitude of 10–10 m2/s measured with the flake coal sample, is more truthful. High temperature and gas pressure, low water saturability, developed pore structure, and high gas adsorption capacity contribute to large CH4 diffusion coefficient. Although the higher rank coal has the larger gas adsorption capacity, the CH4 diffusion coefficient exhibits a “U” shape (first decreasing and then increasing) with the increase of coal rank due to more micropores in low- and high-rank coals than the middle-rank coal. From the bright to dull coals at the same coal rank, the decreasing development of pore structure and gas adsorption capacity causes the decreasing CH4 diffusion coefficient. But compared to the coal rank, the influence of coal macrolithotype on CH4 diffusion coefficient is weaker. In addition, the CH4 diffusion modes in coal mainly are transitional and Fick diffusions in the CBM reservoir and laboratory.
Effects of Hydrogen Addition on the Standoff Distance of Premixed Burner-Stabilized Flames of Various Hydrocarbon Fuels Energy Fuels (IF 3.091) Pub Date : 2018-01-16 Lei Xu, Fuwu Yan, Yu Wang
The quenching distance of premixed hydrocarbon flames is of significant importance for studying flame/wall interactions and for understanding the unburned hydrocarbon emissions of internal combustion engines. Motivated by the fact that the standoff distance of premixed burner-stabilized flames could be used to investigate the behavior of head-on quenching distance of freely propagating flames despite the different physics involved, a parametric investigation on the standoff distances of methane, ethane, and propane burner-stabilized flames was conducted numerically using a detailed chemical kinetic mechanism, with a focus on the effects of hydrogen addition. Specifically, the minimum standoff distance was found to quantitatively correlate with the head-on quenching distance of premixed flames. The variations of the minimum standoff distance as a function of hydrogen fractions were then investigated in detail. The results showed that as hydrogen fraction increased, the minimum standoff distances decreased monotonously for all the hydrocarbon/air flames, with the reduction being most significant for methane fuel. Accompanying kinetic analysis showed that hydrogen addition enhances the heat release process, which promotes the reduction of minimum standoff distance. Subsequently, the dependences of the minimum standoff distance on fuel dilution, equivalence ratios, unburned gas temperatures, and pressures were explored. In addition, the potential to study the parametric dependence on unburned hydrocarbons emissions induced by near-wall flame quenching using the burner-stabilized flame model was discussed. The current study provides a useful approach to quantify the quenching distance of premixed flames, which has practical applications in internal combustion engines. Moreover, the dependence of standoff distance on hydrogen addition and other varying flame parameters can now be more fundamentally understood with the help of detailed chemical kinetics.
Acid-Catalyzed Ring Opening of Furan in Aqueous Solution Energy Fuels (IF 3.091) Pub Date : 2018-01-16 Xiao Liang, Brian S. Haynes, Alejandro Montoya
Simultaneous Removal of SO2 and NOx from Coal-Fired Flue Gas Using Steel Slag Slurry Energy Fuels (IF 3.091) Pub Date : 2018-01-16 Ziheng Meng, Chenye Wang, Xingrui Wang, Yan Chen, Huiquan Li
Adsorption and Dissolution Behaviors of Carbon Dioxide and n-Dodecane Mixtures in Shale Energy Fuels (IF 3.091) Pub Date : 2018-01-16 Chaofan Zhu, Yajun Li, Houjian Gong, Qian Sang, Zijin Li, Mingzhe Dong
CO2 cyclic injection is a promising method for enhanced shale oil recovery. However, the enhanced shale oil recovery mechanism is unclear, especially the adsorption and dissolution of CO2 and oil in kerogen. Therefore, it is of great importance to study the adsorption and dissolution mechanisms of CO2 and oil mixtures in shale. In this study, a new experimental apparatus was designed to test the change in the mole fractions of CO2 and oil before and after adsorption and dissolution at equilibrium conditions. For simplicity, n-dodecane (n-C12) was used as the oil. The adsorption and dissolution amounts of CO2 and n-C12 were obtained using a mathematical method. Moreover, the adsorption and dissolution characteristics of the CO2 and n-C12 mixtures in shale and the effect of pressure on the adsorption and dissolution amounts were studied. Finally, the swelling factor of the shale, which was caused by the dissolution of the mixtures, was calculated from the experimental results. The results show that dissolved n-C12 in shale could be replaced by CO2 when the mole fraction of CO2 in the free phase was larger than a threshold. The adsorption and dissolution amounts of CO2 and n-C12 increased with pressure. The lower pressure and larger mole fraction of CO2 enabled a lower swelling factor of shale. This study provides a straightforward method to experimentally determine the adsorption and dissolution properties of shale, which can be used to evaluate enhanced shale oil recovery by CO2 injection and the geological storage of CO2.
Asphaltene Deposition during Bitumen Extraction with Natural Gas Condensate and Naphtha Energy Fuels (IF 3.091) Pub Date : 2018-01-16 ZhenBang Qi, Ali Abedini, Atena Sharbatian, Yuanjie Pang, Adriana Guerrero, David Sinton
Solvent bitumen extraction processes are alternatives to thermal processes with potential for improved economic and environmental performance. However, solvent interaction with bitumen commonly results in in situ asphaltene precipitation and deposition, which can hinder flow and reduce the process efficiency. Successful implementation requires one to select a solvent that improves recovery with minimal flow assurance problems. The majority of candidate industrial solvents are in the form of mixtures containing a wide range of hydrocarbon fractions, further complicating the selection process. In this study, we quantify the pore-scale asphaltene deposition using two commonly available solvent mixtures, natural gas condensate and naphtha, using a microfluidic platform. The results are also compared with those of two typical pure solvents, n-pentane and n-heptane, with all cases evaluated with both 50 and 100 μm pore-throat spacing. The condensate produced more asphaltenes and pore-space damage than the naphtha and exhibited deposition dynamics similar to that of pentane and heptane. This similarity is due to the presence of a large amount of light hydrocarbon fractions in condensate (∼85 wt % of C5s–C7s) dictating the overall deposition dynamics. Naphtha, which contains heavier fractions (∼70 wt % of C8s–C11s) and aromatic/naphthenic components, generated less asphaltenes and exhibited a slower deposition rate, resulting in less pore damage and overall better performance.
What Fraction of the Asphaltenes Stabilizes Water-in-Bitumen Emulsions? Energy Fuels (IF 3.091) Pub Date : 2018-01-16 J. A. Rocha, E. N. Baydak, H. W. Yarranton
It is hypothesized that only a fraction of the asphaltenes acts to stabilize emulsions and that this fraction consists of the most self-associated (least soluble) asphaltenes. To test the hypothesis, the effects of removing the least soluble versus the most interfacially adsorbed asphaltenes on emulsion stability, film properties, and mass surface coverage were compared. The least soluble asphaltenes were removed by precipitation from solutions of asphaltenes in heptane and toluene. The most adsorbed asphaltenes were removed by separating an asphaltene-stabilized emulsion from its continuous phase. Brine-in-oil emulsions were prepared using organic phases of 10 g/L of the residual asphaltene fractions from the supernatant or continuous phase. The stability of the emulsions was assessed in terms of percentage of water resolved after repeated treatment cycles involving heating at 60 °C and centrifugation at 3500 rpm. The three asphaltenes examined were extracted from a mined oil sand bitumen, a bitumen from a cyclic steam process, and a bitumen from a SAGD process. Only some of the species in the asphaltenes were found to strongly stabilize emulsion, and the size of this fraction ranged from 2% to >65% in the three samples of this study. The most adsorbed, highly stabilizing material tended to be concentrated in the least soluble fraction of the asphaltenes, consistent with the proposed hypothesis. The emulsion stability data were generally consistent with a previously observed threshold of 5 mg/m2 asphaltene surface coverage for stable emulsions. Fractionating the asphaltenes eventually removed enough of the self-associated material that the surface coverage dropped below the threshold and unstable emulsions were observed.
Influence of Asphaltene Polarity on Crystallization and Gelation of Waxy Oils Energy Fuels (IF 3.091) Pub Date : 2018-01-16 Yuzhuo Li, Shanpeng Han, Yingda Lu, Jinjun Zhang
We report for the first time the results from a systematic investigation of how asphaltenes of different polarity affect crystallization and gelation of waxy oils. The more polar asphaltenes were found to be more aromatic in nature and more highly self-aggregated in the solvent. The presence of less polar asphaltenes in the waxy oil reduced the wax appearance temperature and wax precipitation to a greater degree compared to more polar asphaltenes, which was mainly attributed to the difference in the aggregation state of asphaltenes of different polarity. Reducing the polarity of asphaltenes present in the oil also resulted in a lower gelation temperature, lower storage modulus, and lower yield stress, which was probably because the less polar asphaltenes were more similar to wax on the molecular level and, thus, more readily interacting with wax. Notably, a 99% reduction in the yield stress was observed upon the addition of the least polar asphaltenes examined in the present work, in contrast to the 62% yield stress reduction upon the addition of the most polar asphaltenes. This observation may be of industrial significance because it suggests that the crude oil containing less polar asphaltenes may form a softer gel or deposit that is more easily broken or removed. Microscopic analysis showed that the wax crystals precipitated in the presence of less polar asphaltenes have a smaller aspect ratio.
Wettability of reservoir rocks having different polarity by a model nonionic surfactant: fluid imbibition study into crushed rock packs Energy Fuels (IF 3.091) Pub Date : 2018-01-15 Andrei Zelenev, Zlata Grenoble
The imbibition of solutions of a model nonionic surfactant into packed beds of crushed reservoir rocks was studied using the Washburn technique. A linear dependence between the equivalent height of capillary rise and the square root of imbibition time was observed at different stages of imbibition experiments. It has been shown that under the conditions when surfactants did not alter the polarity of rocks, the imbibition rate of surfactant solutions correlated well with the polar non-dispersion component of surface free energy of the rocks. It was possible to compare data obtained for different rocks by normalizing the slopes of imbibition curves over the corresponding slopes determined for a completely wetting fluid, hexamethyldisiloxane (HMDS). Such normalization allowed one to account for substantial differences in the morphology of crushed rock powders. Overall, the observed trends in the imbibition behavior were qualitatively similar to the trends reported previously for the rise of surfactant solutions in single capillaries. The largest qualitative impact of nonionic surfactant was observed in the imbibition into hydrophobic oily sandstone, in which case a surfactant-induced shift to hydrophilicity was observed. Overall, high concentrations were needed in order to observe the impact of surfactant on the imbibition rate.
Unraveling petroleum degradation, maturity, and mixing and addressing impact on petroleum prospectivity: Insights from frontier exploration regions in New Zealand Energy Fuels (IF 3.091) Pub Date : 2018-01-15 Zachary Burton, J. Michael Moldowan, Richard Sykes, Stephan Graham
Determining oil quality is essential to identifying valuable resource accumulations. However, in new areas of exploration, little information is available on the processes affecting resource quality. Geochemical analyses of oil seeps from frontier regions of New Zealand’s east coast illustrate an application of underutilized resource quality assessment techniques. Distributions of n-alkanes and isoprenoids reveal biodegradation, and thus potentially lower oil quality in the “southern” versus the “northern” oil seeps. However, sterane and terpane compounds are unaltered, indicating overall biodegradation of these oils is low to moderate. Additionally, lack of 25-norhopane indicates degradation of southern oils may be solely aerobic. Therefore, any subsurface accumulations are potentially unaffected. Investigation of sterane and hopane isomerization ratios and additional sterane and terpane maturity parameters is paired with diamondoid analyses of oil-to-gas conversion and petroleum mixing. Three distinct -petroleum mixtures are identified among the sampled seeps: 1) a seep composed of an early/peak oil window component and an intensely cracked condensate/wet gas component, 2) seeps solely containing a peak/late oil window component, and 3) seeps composed of a peak/late oil window component and an intensely cracked condensate/wet gas component. Identified components indicate at least three distinct charges or stages of petroleum generation. Black oil components might indicate actively producing source rock in all regions represented by the seeps. Intensely cracked components indicate petroleum mixing via thermogenic gas infiltration, and suggest an effect on oil quality. Important questions concerning migration pathways and timing, ties to New Zealand’s offshore basins, and potential for reservoir entrapment of these petroleum components remain.
Influence of Inherently-Present Oxygen-functional Groups on Coal Fluidity and Coke Strength Energy Fuels (IF 3.091) Pub Date : 2018-01-15 Yuuki Mochizuki, Ryo Naganuma, Naoto Tsubouchi
The effect of various oxygen-containing compounds added and/or inherent O-species on coal fluidity and coke strength has been investigated in detail. When several O-containing compounds, which have different O-containing groups, are added independently to caking coal, the MF value almost decreases, and the extent of the decrease being ether < ketone < lactone < hydroxyl < acid anhydride < < ether/hydroxyl/lactone < carboxyl group. The COOH content in four coals used increases with decreasing C%, and the MF values decrease with increasing the content. The evolution of gaseous O-containing species (CO, CO2, and H2O) during carbonization at 3°C/min of four coals up to 400°C has been studied mainly with a flow-type quartz-made fixed -bed reactor to clarify clear the effect of the amount of O-containing gases evolved on the Gieseler fluidity of coal particles. A positive correlation is found between the amount of CO, CO2, or H2O evolved up to 400°C and the COOH content in coal. However, a negative correlation between MF and O-containing gases evolved up to 400°C is observed. It is suggested that the COOH amount and/or O-containing gases evolved have adverse effects on the thermoplasticity of coal. When the indirect tensile strength of coke prepared from pelletized samples is plotted against MF values, a positive correlation is found, whereas an inverse correlation is observed between the indirect tensile strength and COOH in coals used or the O-containing gases evolved up to 400°C during carbonization. These observations indicate that some of oxygen-functional groups naturally-present in coal have a negative effect on coal fluidity, and that this effect is particularly strong in carboxyl, which can readily be decomposed into gaseous oxygen-containing species during heating up to the initial softening temperature.
Diagenetic controls on the reservoir quality of fine-grained ‘tight’ sandstones: a case study based on NMR analysis Energy Fuels (IF 3.091) Pub Date : 2018-01-14 Hai hua Zhu, Dakang Zhong, Tingshan Zhang, Guangcheng Liu, Jingli Yao, Chuanhang He
Accurate description of diagenetic controls on reservoir quality in ‘tight’ sandstones can be difficult because of the inherent fine grain size and complex components of such oil reservoirs. In this study, petrological techniques and nuclear magnetic resonance (NMR) analysis were applied to fine-grained tight sandstones with varying grain sizes in order to reveal the diagenetic controls on reservoir quality. Results show that macropores in tight sandstones occur mainly as intergranular and dissolution pores, whereas micropores are distributed within ductile rock fragments, clay and mica minerals, as well as occurring as dissolution micropores. Pore size distribution (PSD) / T2 spectra display three distribution patterns: i) a macropore-dominant bimodal distribution, ii) a macropore-micropore bimodal distribution, and iii) a micropore-dominant skewed distribution. A decrease in grain size correlates with weaker framework support of particles and thus more intensive mechanical compaction, resulting in the loss of both macroporosity and microporosity. Consequently, PSD change from macropore-dominant bimodal distributions to micropore-dominant skewed distributions as the pore type shifts from being dominated by macropores to intragranular micropores. In fine-grained sandstones, an increase in the abundance of ductile components corresponds to a loss of total porosity, related to the decrease in abundance of macropores, whereas the change in micropore abundance is negligible. This change is reflected in PSD by a shift from macropore-dominant bimodal distributions to macro-micropore bimodal distributions. The authigenic minerals in tight sandstone reservoirs occur mainly as late-stage carbonate minerals, and the precipitation of this carbonate cement preferentially occurs within macropores. When carbonate cement content is low, it has a limited influence on total porosity. However, it does significantly reduce the connectivity of the pore system, which is different to what might be expected in conventional sandstone reservoirs. Therefore, particle grain size, the abundance of ductile components and late-stage cementation all contribute to the prediction of reservoir quality in oil-bearing tight sandstones.
Micromorphology of asphalt by polymer and carbon nanotubes modified through molecular dynamics simulation and experiments: role of the strengthened interfacial interactions Energy Fuels (IF 3.091) Pub Date : 2018-01-13 Peng Wang, Fei Zhai, Ze-jiao Dong, Li-zhi Wang, Jian-ping Liao, Gui-rong Li
Polymer modifiers have been used to improve the performances of asphalt binders in pavement engineering. The modifying effect of polymer on asphalt is largely depended on the morphological characteristics of polymer–modified asphalt. The morphologies of polymer–modified asphalt are composed of polymer–rich phase, asphaltene–rich phase, and the interphase between the two phases. Interfacial interactions importantly contribute to morphology but are commonly overlooked. In this study, carbon nanotubes (CNTs) were selected to improve the interfacial interactions of polymer–modified asphalt. Fluorescence microscope (FM), scanning electron microscope (SEM), micro–Raman spectra (MRS) and molecular dynamics simulation (MD) were used to capture the characteristics of the interphase and polymer–rich phase. CNTs–polymer–modified asphalt involves stronger intermolecular forces than those in asphalt modified by only styrene–butadiene–styrene (SBS) or CNTs only. This discrepancy highlights the intensified interfacial interaction in the former material. Raman peak and MD findings reveal that the C=C of CNTs interacted with the alkanes and aromatic hydrocarbons of asphalt. SBS were entwined or surrounded with CNTs through the π–π conjugation of the benzene rings of the two components. Consequently, synergistic effect enhanced the intermolecular force between SBS and CNTs in the interphase. SEM results indicated that CNTs were enriched in the interphase, enhancing mechanical anchorage between the polymer and asphalt. As a results, CNTs increased the roughness of the interphase and produced a prominent cage construction of polymer–rich phase. Moreover, the observed pull–out behaviors of CNTs alleviated interfacial failure. FM images displayed that CNTs enhanced the swelling degree of polymer–rich phase. This effect was realized because CNTs served as a tunnel for transporting saturates, aromatics, and small resin molecules, as shown by MD analysis. This work revealed the importance of the interfacial interactions on the micromorphologies of polymer–modified asphalt.
Study on the effects of different carrier gases on characteristics of supersaturated environment in the one/multi-section growth tube Energy Fuels (IF 3.091) Pub Date : 2018-01-12 Yan Yu, Junchao Xu, Jun Zhang, Guangchuang Chen, Hui Zhong
The supersaturation profiles in one/multi-section growth tube were predicted under the conditions of different carrier gases for two kinds of typical supersaturation achieving methods. The results show that Lewis number (Le) of the carrier gas is an important factor affecting the supersaturation profiles. For the one-section growth tube, the carrier gas with smaller Le is beneficial to higher level and flatter trend of supersaturation profiles for method 1, where supersaturated environment is achieved by a cool saturated flow into a warm-walled growth tube. However, for the carrier gas of larger Le, the higher level but less stable supersaturation profiles are presented from method 2, where a warm saturated flow into a cold-walled growth tube. With the carrier gas of large Le (>1) from method 1 and the carrier gas of small Le (<0.5) from method 2, efficient supersaturated environment cannot be achieved under the ordinary condition. In the multi-section growth tube, the more minimum number of the sections is selected for stable supersaturation profiles with the carrier gas of larger Le. Additionally, the sections of flatter supersaturated environment are closely related to the achieving methods of supersaturation environment, the whole length of the growth tube and radial positions.
Activated Carbon for Capturing Hg in Flue Gas under O2/CO2 Combustion Conditions. Part A: Experimental and Kinetic Study Energy Fuels (IF 3.091) Pub Date : 2018-01-12 Hui Wang, Shen Wang, Yufeng Duan, Ya-ning Li, Yuan Xue, Zhanfeng Ying
This study evaluated the mercury sorption by activated carbon(AC) under the O2/CO2 atmosphere in a fixed-bed reactor. Effects of the oxygen concentration on the mercury sorption efficiency under both the air and oxy-fuel atmosphere were explored. The kinetic studies were also used to predict the mercury sorption process by the pseudo-first-order model and the intraparticle diffusion model in this work. The experimental results indicated that the mercury sorption capacity of AC increased with the increased oxygen concentration under both the air and oxy-fuel atmosphere. Oxygen might increase the oxidation of mercury by the Mars-Maessen way. A high CO2 concentration promoted AC to generate more active sites under the oxy-fuel atmosphere. Besides, the results of the kinetic analysis illustrated that the pseudo-first-order model showed a better agreement with the experimental data compared to the intraparticle diffusion model. These experimental and theoretical results in this work are helpful in mercury capture under the oxy-fuel atmosphere.
Determination of the Absolute Adsorption Isotherms of CH4 on Shale with Low-field Nuclear Magnetic Resonance Energy Fuels (IF 3.091) Pub Date : 2018-01-12 Yueliang Liu, Chen Wang
Understanding of the absolute adsorption behavior of CH4 on shale is critically important in estimating shale-gas storage in shale gas reservoirs. In this work, two approaches are applied to obtain the absolute adsorption isotherms of CH4 on shale samples. In the first approach, we firstly measure the excess adsorption isotherms of CH4 on two shale samples at the temperature of 298.15 K and pressures up to 12.0 MPa. Then, Grand Canonical Monte Carlo (GCMC) simulations are used to calculate the adsorption-phase density; such density values are consequently applied to calibrate the measured excess adsorption and obtain the accurate absolute adsorption isotherms. As for the second approach, we apply the low-field nuclear magnetic resonance (NMR) method to describe the absolute adsorption of CH4 on shale. A NMR-based setup is designed to measure the T2 spectrum distributions in shale samples by injecting CH4 into dry shale samples. The injecting pressure is set up to 12.0 MPa, which is similar to the conditions used in the excess adsorption measurements. Based on the measured T2 spectrum and the injected molar amount of CH4, the adsorbed molar quantity of CH4 can be assessed on the shale samples at specific conditions. We then compare the absolute adsorption isotherms obtained from both method and evaluate the capability of the NMR approach in determining the absolute adsorption of CH4 on shale. With GCMC simulations, we find that the calculated adsorption-phase density strongly correlates with the system pressure. By taking into consideration the adsorption-phase density, the absolute adsorption isotherm is always higher than the measured excess adsorption curves; that is, the measured excess adsorption underestimates the actual adsorption capacity on shale. Based on the comparison results, the adsorption isotherms obtained from the NMR method have a good agreement with the corresponding absolute adsorption isotherms after calibrating with the adsorption-phase density; it indicates that the low-field NMR-based setup is a good tool in obtaining the absolute adsorption isotherms of CH4 on shale.
A new model and insight of hydrate film lateral growth along gas-liquid interface considering natural convection heat transfer Energy Fuels (IF 3.091) Pub Date : 2018-01-12 Zheng Liu, Hao Li, Litao Chen, Baojiang Sun
Modeling of hydrate growth at the interface between gas and aqueous phases is critical for evaluating the growth rate of hydrate film and initial thickness in the oil and natural gas industries. However, most existing heat transfer models in presumption and hypothesis possess logical or physical deficiencies, which may lead to wide deviations when predicting results. In this work, a new model of hydrate film lateral growth along a planar gas-liquid boundary is developed, which considers natural convection heat transfer. This model not only correlates subcooling, which is generally regarded as the main controlling factor in the process of hydrate growth, but also describes a quantitative relation with experimental temperature that has never been embodied in previous models. In combination with the experimental data in this paper and the previous literature, a comparison of the simulation between the proposed model and typical heat transfer models is provided. The simulated results show that this model agrees well with the measured data for both the bubble surface and planar gas-liquid interface. Furthermore, estimations of methane hydrate film thickness at a subcooling range of 0.3-3 K are performed using the new model and analyzed in contrast with data available in the literature. This work simultaneously yields a subtle observation and investigation into hydrate film propagation at the diverse position of gas-liquid interface, and provides new insights into qualitatively characterizing heat transfer efficiency of hydrate film frontier by introducing a dimensionless number β.
Structure-reactivity relationship in fast pyrolysis of lignin into monomeric phenolic compounds Energy Fuels (IF 3.091) Pub Date : 2018-01-12 Jun Hu, ShiLiang Wu, Xiaoxiang Jiang, Rui Xiao
The structure-reactivity relationship in fast pyrolysis of lignin for monomeric phenolic compounds was studied on seven lignins from hardwood, softwood and grass. The distribution of elements, functional groups, phenylpropane units and interunit linkage bonds varied greatly across the lignins. Lignins from hardwood and grass prepared with mild conditions presented more C-O linkages. Py−GC/MS showed that the cleavage of unstable C-O linkages dominated the pyrolysis reaction at low temperature, and the total yields of monomers peaked at 700oC for most lignins. 4-vinylphenol produced from acid extracted corn stalk lignin (ACL) reached up to 4.77wt% at 700oC. Pyrolysis of grass lignins and woody lignins which had more unstable C-O linkages exhibited higher total yields of monomers. The pyrolysis behavior of lignin at low temperatures is closely related to its structural characteristics. Pyrolyzed at 500oC, the total yields of monomeric aromatics was highly linearly correlated with the frequencies of C-O linkages (R2=0.86). This work demonstrates the significance of selecting the right lignin for producing monomeric aromatic compounds.
Impact of Modified Seawater on Zeta Potential and Morphology of Calcite and Dolomite Aged with Stearic Acid Energy Fuels (IF 3.091) Pub Date : 2018-01-12 Hasan Al-Hashim, Ahmed Amara Kasha, Wael Abdallah, Bastian Sauerer
Zeta potential measurements and microscopic surface characterization and imaging were conducted on calcite and dolomite crystals aged in stearic acid model oil and exposed to different synthetic brines representing different potential scenarios of injected seawater from the Arabian Gulf. Calcite particles were negatively charged in deionized water and maintained negative surface charges in all tested brines, except in diluted Arabian Gulf seawater that contained higher concentration of Ca2+ and Mg2+ ions. Dolomite particles were positively charged in deionized water as well as in all tested brines, except in diluted Arabian Gulf seawater that contained four times higher concentration of SO42- ions. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) experiments on cleaved calcite and dolomite chips showed different morphological changes when both samples are aged in model oil and then treated with brines. Calcite surface dissolution was observed in addition to stearic acid deposition. Surface elemental analysis using Energy-Dispersive Spectroscopy (EDS) showed Mg2+ and SO42- ions adsorb preferably on locations where stearic acid is deposited. The finding that stearic acid was adsorbing stronger on dolomite than on calcite could indicate why the tested brines were less efficient to change the zeta potential of the dolomite systems. The current study concludes that manipulating the concentration of potential determining ions present in the Arabian Gulf seawater, especially Mg2+ and SO42- ions, will alter the surface charges of aged calcite and dolomite samples as well as their surface morphology.
Co-Production of Hydrogen and Copper from Copper Waste using a Thermochemical Cu-Cl Cycle Energy Fuels (IF 3.091) Pub Date : 2018-01-12 Farrukh Khalid, Ibrahim Dincer, Marc Rosen
A novel hybrid Cu-Cl thermochemical cycle is developed and assessed for the co-production of hydrogen and copper using copper waste. An experiment is also conducted to establish the high temperature electrolytic step as a proof of concept. A detailed parametric study is conducted to assess the effects of such parameters as process step temperature and energy efficiency of the electrical power plant that provides electricity to the cycle on the energy and exergy efficiencies of the overall cycle. The values of the energy and exergy efficiencies of the cycle are 31.8% and 69.7%, respectively. The maximum specific exergy destruction occurs in the electrolytic step. The results show that the proposed cycle performs better in terms of energy and exergy efficiencies compared to similar four-step Cu-Cl cycles. By using the proposed cycle, a new avenue may be open for copper waste to be more advantageously managed, potentially enhancing the sustainability of the relevant processes through improved environmental protection and resource recovery.
Reduction and Oxidation Kinetics of Fe–Mn-Based Minerals from Southwestern Colombia for Chemical Looping Combustion Energy Fuels (IF 3.091) Pub Date : 2018-01-12 Francisco J. Velasco-Sarria, Carmen R. Forero, Eduardo Arango, Juan Adánez
The oxygen carrier (OC) is the main component of the chemical looping combustion (CLC), process. Most OCs have been developed synthetically using an active metal oxide combined with an inert material. When solid fuels are used, the OC becomes mixed with the ashes generated during the CLC process and has to be removed, thereby increasing costs. As a result, there is growing interest in the use of low-cost OCs based on manganese and iron. Given the widespread use of coal to produce energy, there is a trend toward the study of the CLC process using solid fuels, since this process has the lowest energy penalties of all the combustion methods involving CO2 capture. Coproducts from the exploitation of Mn and Fe ores have been studied. These materials were selected from a group of eight minerals with Fe and Mn present in their composition, extracted from mines located in southwestern Colombia. The material selection process was based on crushing strength analysis and reactivity in thermographic analysis (TGA), using CH4 as fuel. Two materials were selected, one based on Fe and another based on Mn, which presented the best behavior in their respective group. It was found that the studied two materials were more reactive with H2 and CO than with CH4. This was demonstrated by performing a kinetic study using a shrinking core model (SCM). The selected Mn-based oxide was evaluated to identify whether it had the properties required for chemical looping with oxygen uncoupling (CLOU), commonly found in Mn minerals with a high silica content. However, no evidence to this effect was found in experiments at 1000 °C using N2 for OC decomposition and air as an oxidizing gas. The Mn ore showed the highest reactivity of all the studied materials, with a rate index of 11.9%/min in experiments at 950 °C using H2 as the reducing gas. Finally, it can be concluded that the presence of silica improves the reactivity of the Mn ore, making it a promising carrier for use in in situ gasification chemical looping combustion (iG-CLC) technology.
Coal Refining Chemical Looping Systems with CO2 as a Co-Feedstock for Chemical Syntheses Energy Fuels (IF 3.091) Pub Date : 2018-01-12 Mandar Kathe, Peter Sandvik, Charles Fryer, Fanhe Kong, Yitao Zhang, Gabrielle Grigonis, Liang-Shih Fan
This study quantifies the advantages of a chemical looping reducer reactor modularization strategy that leverages two or more reducer reactors operating in parallel to enhance syngas production beyond what is achievable by a single reducer reactor or conventional processes. The modularized system incorporates CO2 capture and utilization as a feedstock in an iron–titanium composite metal oxide based chemical looping system to enhance coal based chemical production. Simulations conducted in ASPEN Plus software suggest that adopting a cocurrent moving bed reducer reactor based modularization strategy can improve syngas yield by greater than 11% over a single chemical looping reducer reactor. Experiments conducted on a bench scale reducer reactor confirm the findings of the simulations. The modularization simulation was scaled up and incorporated into commercial sized methanol and acetic acid production plants. Chemical looping modularization demonstrates the ability to reduce coal consumption by 25% over a baseline coal gasification process, compared to 15% reduction if a single chemical looping reducer reactor is used instead of the modular strategy, for 10 000 ton per day methanol production. Integration into a commercial scale acetic acid plant shows conditions in which the process can operate as a CO2 neutral or negative system, where the process was consuming more CO2 than it produces. These results indicate the potential for significant feedstock reduction in large-scale coal to chemical processes, like methanol, acetic acid, formic acid, and oxalic acid.
Investigation of Water Interactions with Petroleum-Derived and Synthetic Aviation Turbine Fuels Energy Fuels (IF 3.091) Pub Date : 2018-01-12 Zachary J. West, Takahiro Yamada, Christopher R. Bruening, Rhonda L. Cook, Susan S. Mueller, Linda M. Shafer, Matthew J. DeWitt, Steven Zabarnick
While undesirable in aviation fuel systems, water is both ubiquitous and tenacious; thus, interactions between water and aviation turbine fuel occur regularly. From a fuel user perspective, it is important to know, understand, and be able to predict such fuel–water interactions, e.g., water solubility, water settling rate, and interfacial tension, for proper mitigation. We explore these interactions as well as surface tension of both petroleum-derived and alternative jet fuels to compare potential differences between product compositions on these physical interactions. Observations indicate a positive, nonlinear correlation between water solubility and both aromatic content and temperature (from 0 to 50 °C). Water settling rates appear to follow a Stokes’ law model; therefore, bulk chemical composition indirectly influences settling rates via density and viscosity. Finally, surface tension appears positively correlated to sample density, while interfacial tension is correlated to both surface tension and fuel aromatic content.
Solar-Thermal Pyrolysis of Mallee Wood at High Temperatures Energy Fuels (IF 3.091) Pub Date : 2018-01-12 Hongwei Wu, Daniel Gauthier, Yun Yu, Xiangpeng Gao, Gilles Flamant
This study reports solar-thermal pyrolysis of mallee wood powders driven by direct concentrated solar radiations at different temperatures (1540, 1740, and 1930 °C), heating rates (320, 800, and 3200 °C/min), and holding times (0 and 5 min). Under such severe pyrolysis conditions, solar-thermal pyrolysis of mallee wood produces predominantly volatiles (≥90 wt %), with very low char yields (≤10 wt %), as reported on a dry basis. Majorities of inherent alkali and alkaline earth metallic (AAEM) species are also released into the gaseous phase. The severe pyrolysis conditions also lead to the low reactivity of char products as a result of not only the char carbon structure becoming ordered and graphitized (as evidenced by the Raman data) but also significant losses of catalytic AAEM species in the char. For example, during the solar-thermal pyrolysis of mallee wood at 1930 °C, 800 °C min–1, and 5 min holding time, the char yield is only ∼5 wt %, the retentions of Na and Mg are ∼1%, the retentions of K and Ca are only 13 and 35%, respectively, and the char is less reactive. Therefore, despite the low char yield, char conversion is still a critical consideration in the design and operations of solar-thermal reactors under these conditions because the char is very inert.
Hydrodesulfurization of Thiophene on Activated Carbon Fiber Supported NiMo Catalysts Energy Fuels (IF 3.091) Pub Date : 2018-01-12 Yogendra Nath Prajapati, Nishith Verma
Experimental investigation of laminar flame speed measurement for kerosene fuels: Jet A-1, surrogate fuel and its pure components Energy Fuels (IF 3.091) Pub Date : 2018-01-11 Yi Wu, Vincent Modica, Xilong Yu, Frederic Grisch
The present work investigated the laminar flame speed measurement of kerosene-relevant fuel, including Jet A-1 commercial kerosene, and surrogate kerosene fuel and its pure components (n-decane, n-propyl-benzene and propyl-cyclohexane), using a high-pressure Bunsen flame burner. The OH* chemiluminescence technique and the kerosene-PLIF technique were used for flame contours detection in order to calculate the laminar flame speed. The experiments were firstly conducted for n-decane/air flame at T = 400 K, φ=0.6-1.3 and atmospheric pressure conditions in order to validate the whole experimental system and measurement methodology. The laminar flame speed of Jet A-1/air, surrogate/air and pure kerosene component (n-decane, n-propyl-benzene and propyl-cyclohexane) was then measured under large operating conditions, including temperature T = 400-473 K, pressure P = 0.1-1.0 MPa and equivalence ratio φ=0.7-1.3. It was found that these three pure components of kerosene have very similar laminar flame speed. By comparing the experimental results of surrogate kerosene and Jet A-1 commercial kerosene, it was observed that the proposed surrogate kerosene, i.e., mixtures of 76.7wt% n-decane, 13.2wt% n-propyl-benzene and 10.1wt% propyl-cyclohexane, can appropriately reproduce the flame speed property of Jet A-1 commercial kerosene fuel. The experimental results were further compared with simulation results using a skeletal kerosene mechanism.
Experimental Investigation of the Geochemical Interactions between Supercritical CO2 and Shale: Implications for CO2 Storage in Gas-bearing Shale Formations Energy Fuels (IF 3.091) Pub Date : 2018-01-11 Yi Pan, Dong Hui, Pingya Luo, Yan Zhang, Lei Sun, Ke Wang
Interactions between injected CO2 and shale formation during the process of CO2 sequestration with enhancing shale gas recovery (CS-EGR) may alter the physical and chemical properties of the rock, affecting the efficiency of CO2 storage as well as CH4 production. To better understand these interaction-induced changes in shale properties, two shale samples selected from marine Longmaxi formation and terrestrial Chang-7 Member of Yanchang formation were first reacted with supercritical CO2 (scCO2) in a laboratory batch reactor at 80 ℃ and 15 MPa with different time intervals, then characterization methods were designed to access the geochemical changes including optical microscope (OM), X-ray diffraction (XRD), element analysis (EA), low-pressure gas adsorption (LPGA) and fourier transform infrared spectroscopy (FTIR). The results indicate that the nanopore structure system of the two shale samples was significantly changed after scCO2-shale interactions due to the scCO2-induced extraction of hydrocarbons, chemical reactions in minerals and swelling effect in clay minerals as well as organic matter. However, after exposure to scCO2 the variation trend of pore structure parameters between the marine and terrestrial shale sample was quite different, which was related to the huge discrepancies in terms of mineralogy and geochemical properties between them. For marine Longmaxi shale sample, the pore surface area and pore volume obviously decreased after a relatively short period of scCO2 treatment, whereas an opposite trend was observed in terrestrial Chang-7 sample after long-term scCO2 treatment. In addition, an obvious decrease in fractal dimensions for marine Longmaxi sample was also observed after scCO2 exposure, reflecting that the degree of pore surface roughness and pore structure complexity were reduced, whereas the terrestrial Chang-7 sample exhibited an opposite trend. The results contribute to the understanding of the potential factors for the pore structure evolution during long-term CO2 storage and the possible effect on the CS-EGR process.
A Coupled Structural and Kinetic Model of Lignin Fast Pyrolysis Energy Fuels (IF 3.091) Pub Date : 2018-01-11 Abraham J. Yanez-McKay, Pradeep Natarajan, Wenjun Li, Ross Mabon, Linda J. Broadbelt
Lignocellulosic biomass is a promising feedstock for renewable fuels and chemical intermediates; in particular, lignin attracts attention for its favorable chemical composition. One obstacle to lignin utilization and valorization is the unknown chemical mechanism that gives rise to the complex product distributions observed upon deconstruction. Among possible deconstruction chemistries, fast pyrolysis is promising due to its short residence time, thus enabling high volume production. However, the chemistry is inherently complex, thereby hampering the creation of detailed kinetic models describing pathways to specific low molecular products. To this end, we have created a detailed kinetic model of lignin decomposition via pyrolysis comprised of 4313 reactions and 1615 species based on pathways suggested by pyrolysis of model compounds in the literature. Using a rule-based reaction network generation approach, a pathways-level reaction network is proposed to predict the evolution of macromolecular species and the formation of various low molecular weight products identified from experimental studies. This reaction network is coupled to a structural model of wheat straw lignin via a kinetic Monte Carlo framework to simulate lignin fast pyrolysis. The mass yields of and speciation within four commonly-observed fractions, viz., light gases, an aqueous phase containing water and small oxygenates, char, and a highly complex aromatics fraction, are compared to an experimental report of a putatively similar biomass source. Additional capabilities of the model include the time-resolved prediction of volatilization profiles and the evolution of the molecular weight distribution, which may assist in efforts to valorize lignin to a higher degree than that achieved by current approaches.
Using Lead Isotopes to Assess Source and Migration of Lead during Thermal Treatment of Municipal Solid Waste Influenced by Air Excess Ratio Energy Fuels (IF 3.091) Pub Date : 2018-01-11 LI-Ming Shao, Yang Li, Hua Zhang, Pin-Jing He
The behavior of lead (Pb) during thermal treatment of municipal solid waste (MSW) is a serious environmental concern. The migration of Pb during pilot-scale thermal treatment of MSW with controlled air excess ratio (ER) was studied focusing on Pb contents and isotope ratios analysis. Different ERs showed different Pb distribution behaviors in fly ash (FA) from MSW incineration, owing to the change of Pb migration from different MSW components. Although the Pb contents in FA under the oxidizing condition increased significantly with the increase of ER (almost 100% from ER = 1.0 to ER = 1.3), the major sources (i.e., papers and plastics) contributing Pb to FA were similar based on the Pb isotope identification. This suggested that the migration of Pb from these MSW components was promoted in a high oxygen environment. In contrast, the Pb contents in FA under the low oxygen condition (ER = 0.3−0.5) were similar, and rubbers became the major source of Pb in FA in the low oxygen environment instead of papers. In the low oxygen environment the migration of Pb in rubbers and papers was promoted and inhibited, respectively, as indicated by the isotopic analysis combined with the micro-X-ray fluorescence and diffraction analyses.
Study on temperature characteristics of hydrate slurry during cyclopentane-methane hydrate formation Energy Fuels (IF 3.091) Pub Date : 2018-01-11 Jing Cai, Ya-Fei Hu, Yu Zhang, Chun-Gang Xu, Zhao-Yang Chen, Qiunan Lv, Xiao-Sen Li
In this work, the temperature characteristics of hydrate slurry related to transition heat in the cyclopentane (CP)/methane (CH4) hydrate formation process were systematically investigated. A crystallizer with a special heat-insulating layer of aerogel was designed to hold the transition heat, and the hydrate slurry could be heated in the crystallizer. Temperatures were measured in the process of the hydrate formation under the conditions of different operating pressures, volumes of solution, ways of gas injection and volume ratios of CP to water. The highest temperature of hydrate slurry (Th) and the maximum temperature difference (∆Tmax) relative to the initial temperature were adopted to evaluate the influence of different conditions. The experimental results indicated that the hydrate formation interface and thermal interface obviously move from the initial gas/CP interface and CP/water interface towards the bulk solution. Both the increase of operating pressure and the decrease of solution volume have positive effect on enhancing the hydrate slurry temperature. In addition, the volume ratio of CP to water also significantly affects the fluctuation of the hydrate slurry temperature. The hydrate slurry could be heated up to 294.45 K and the ∆Tmax of 16.30 K could be obtained, and such high heat could be effectively collected and used elsewhere.
Fluidized Bed Catalytic Pyrolysis of Eucalyptus over HZSM-5: Effect of Acid Density and Gallium Modification on Catalyst Deactivation Energy Fuels (IF 3.091) Pub Date : 2018-01-11 Charles A. Mullen, Paul C. Tarves, Lucas M. Raymundo, Emerson L. Schultz, Akwasi A. Boateng, Jorge O. Trierweiler
Catalytic fast pyrolysis of eucalyptus wood was performed on a continuous laboratory-scale fluidized bed fast pyrolysis system. Catalytic activity was monitored from use of fresh catalyst up to a cumulative biomass/catalyst ratio (B/C) of 4:1 over extruded pellets of three different ZSM-5 catalysts by tracking CO, CO2, H2, and C2H4 production and bio-oil quality. The catalysts employed were extruded HZSM-5 with two different silica/alumina ratios (30 and 80) as well as one modified with Ga (SiO2/Al2O3 = 30) by ion exchange, which was reduced under H2 prior to pyrolysis. The deactivation of the catalysts over the course of the experiment was reflected in the decline in deoxygenation activity, following the order HZSM-5 (30) > HZSM-5 (80) > GaZSM-5 (30). HZSM-5 (30) lost most of its activity before a cumulative B/C of 2:1 was reached, while HZSM-5 (80) still showed significant deoxygenated activity at this exposure level. GaZSM-5 (30) still showed deoxygenation activity at B/C of >4:1. The improvement exhibited by HZSM-5 with an increasing SiO2/Al2O3 ratio was attributed to reduced acid site density that decreased the propensity for coke formation as a result of reactions occurring between substrates at adjacent active acid sites. For reduced GaZSM-5, initial dehydrogenation activity aided in the production of aromatics by the olefin oligomerization and aromatization route up to B/C of ∼1.5:1, after which Ga became completely oxidized; however, the oxidized GaZSM-5 catalyst continued to exhibit improved decarbonylation and decarboxylation activities.
Gasification Reactivity and Structure Evolution of Metallurgical Coke under H2O/CO2 Atmosphere Energy Fuels (IF 3.091) Pub Date : 2018-01-11 Runsheng Xu, Bowen Dai, Wei Wang, Johannes Schenk, Anrin Bhattacharyya, Zhengliang Xue
The metallurgical properties and the microstructure of coke after gasification reaction with pure H2O and pure CO2 were investigated in this study. Moreover, the first-principles calculation was conducted to study the reaction process of the carbon with pure H2O and pure CO2. The results show that the CRI (coke reaction index) increases sharply and the CSR (coke strength after reaction) decreases sharply, when the cokes are gasified with H2O as compared to CO2. The scanning electronic microscopy images and the coke panoramagrams show that H2O more easily leads to the generation of large pores (>500 μm) and destroys the coke structure than CO2. The X-ray diffraction results indicate that the arrangement of carbon atoms of coke becomes regular and the ordered degree of coke increases after reaction with CO2 and H2O; however, after being gasified with H2O, the cokes have a higher ordered degree than with CO2. The results of the first-principles calculation show that the H2O molecule is more likely to react with carbon as compared to the CO2 molecule due to the lower energy barriers of H2O adsorption and H2 formation. The M2 → FS reaction process is the controlled step of the C-H2O reaction process, as well as in the C-CO2 reaction system.
Review of Pulverized Combustion of Non-Woody Residues Energy Fuels (IF 3.091) Pub Date : 2018-01-11 Miriam Rabaçal, Sandrina Pereira, Mário Costa
The intense use of wood-derived fuels in (co)firing processes results in an enormous pressure on the forest. In order to alleviate this pressure and to proceed with the CO2 emissions reduction process, it is necessary to increase the use of non-woody residues, in particular herbaceous materials and agricultural residues. (Co)firing using such residues can cause a number of problems due to the presence of alkali metals, chlorine, and other ash-related impacts as well as corrosion of metallic surfaces and particulate matter emissions. This may limit the variety of biomass residues that can actually be used in (co)firing processes. This review aims to summarize recent developments in the combustion of pulverized non-woody residues and includes experimental and numerical studies of single particle combustion and combustion in small- and large-scale furnaces. The review provides an overview of the properties of non-woody residues, describes the existing research facilities to study the subject, and summarizes the experimental studies on the combustion of non-woody residues, including studies on single particle combustion, drop tube furnaces and entrained flow reactors, and large-scale furnaces. The review also concentrates on numerical modeling, namely on the formulation of combustion models and their application in computational fluid dynamics. Finally, the main conclusions are summarized and the research needs listed.
Production of Hydrotreated Jatropha Oil Using Co–Mo and Ni–Mo Catalysts and Its Blending with Petroleum Diesel Energy Fuels (IF 3.091) Pub Date : 2018-01-11 Shailesh J. Patil, Prakash D. Vaidya
Jatropha oil is a prospective non-edible resource for green diesel manufacturing. In this work, diesel-range hydrocarbons (mostly C15–C18 n-paraffins) were produced from the hydrotreatment of jatropha oil over traditional CoMo/Al2O3 and NiMo/Al2O3 catalysts in a fixed-bed reactor. The reaction variables were varied as follows: temperature, 563–653 K; pressure, 1.5–3 MPa; H2/oil ratio, 200–800 (v/v); and weight hourly space velocity, 1–4 h–1. Oil conversion was maximized (Co–Mo, 97%; Ni–Mo, 88.6%) at T = 653 K and P = 3 MPa. The hydrocarbon yield at these conditions was 62.6% (Co–Mo) and 63% (Ni–Mo). These findings were juxtaposed with our latest results on the hydrotreatment of the non-edible karanja oil. From the first-order plots of conversion of triglycerides in jatropha oil, rate constants and energy of activation were found. To improve the cold flow properties of the hydrotreated jatropha oil without isomerization, it was blended with usual diesel in varying proportions. As the concentration of usual diesel in such mixtures increased, the viscosity, cetane number, and pour point decreased. Employing tailored blends of hydrotreated vegetable oil and petroleum diesel thus appeared preferential. Finally, the performance of Co–Mo and Ni–Mo catalysts prepared by wet impregnation was tested, but the activity of the commercial catalysts was superior.
Numerical Study on Premixed Methane–Air Flame Propagation in a Confined Vessel at Low Initial Temperature Energy Fuels (IF 3.091) Pub Date : 2018-01-11 Gan Cui, Zili Li, Hongbo Li, Zhenxiao Bi, Shun Wang
Compositional Characterization of Pyrolysis Fuel Oil from Naphtha and Vacuum Gas Oil Energy Fuels (IF 3.091) Pub Date : 2018-01-11 Nenad D. Ristic, Marko R Djokic, Elisabeth I. P. Delbeke, Arturo Gonzalez Quiroga, Christian Victor Stevens, Kevin Marcel Van Geem, Guy B Marin
Steam cracking of crude oil fractions gives rise to substantial amounts of a heavy liquid product referred to as Pyrolysis Fuel Oil (PFO). To evaluate the potential use of PFO for production of value-added chemicals a better understanding of the composition is needed. Therefore, two PFO’s derived from naphtha (N-PFO) and Vacuum Gas Oil (V-PFO) were characterized using elemental analysis, SARA fractionation, nuclear magnetic resonance (NMR) spectroscopy and comprehensive two-dimensional gas chromatography (GC × GC) coupled to a flame ionization detector (FID) and time-of-flight mass spectrometer (TOF-MS). Both samples are highly aromatic, with molar hydrogen-to-carbon (H/C) ratios lower than 1 and with significant content of compounds with solubility characteristics typical for asphaltenes and coke, i.e. n-hexane insolubles. The molar H/C ratio of V-PFO is lower than the one measured for N-PFO, as expected from the lower molar H/C ratio of the VGO. On the other hand, the content of n-hexane insolubles is lower in V-PFO compared to the one in N-PFO, i.e. 10.3 ± 0.2 wt.% and 19.5 ± 0.5 wt.%, respectively. This difference is attributed to the higher reaction temperature applied during naphtha steam cracking, which promotes the formation of poly-aromatic cores and at the same time scission of aliphatic chains. The higher concentrations of purely aromatic molecules present in N-PFO is confirmed via NMR and GC × GC – FID/TOFMS. The dominant chemical family in both samples are diaromatics, with a concentration of 28.6 ± 0.1 wt.% and 27.8 ± 0.1 wt.% for N-PFO and V-PFO, respectively. Therefore, extraction of valuable chemical industry precursors such as diaromatics and specifically naphthalene is considered as a potential valorization route. On the other hand, hydro-conversion is required to improve the quality of the PFO’s before exploiting them as a commercial fuel.
In-situ study on K2CO3-catalyzed CO2 gasification of coal char: interactions and char structure evolution Energy Fuels (IF 3.091) Pub Date : 2018-01-11 Huaili Zhu, Xingjun Wang, Fuchen Wang, Guangsuo Yu
To investigate the interactions between K2CO3 and coal char, a fixed-bed reactor was used to conduct catalytic pyrolysis and gasification of coal char. An in-situ Raman spectroscopy system was applied to characterize the evolution of char structure. Three different ranks of Chinese coals were deashed firstly and pyrolyzed to chars before experiment. In catalytic pyrolysis of coal char, the release of CO proved that reactions occurred between K2CO3 and char and the release of small amount of CO2 was connected with the oxygen content. In-situ Raman spectra results showed that the char structure order decreased with rising temperature for the production of intermediate. During gasification process, the char structure order decreased first and then increased attributed by the evaporation of K at high temperature. The ex-situ data revealed that the intermediate did not exit at room temperature. For better understanding of the true form of chars at high temperature, an in-situ Raman spectrometer is necessary.
Mercury in Polish Coking Bituminous Coals Energy Fuels (IF 3.091) Pub Date : 2018-01-11 Piotr Burmistrz, Krzysztof Kogut, Marta Marczak, Tadeusz Dziok, Jerzy Górecki
Poland emits 10.58 Mg of mercury to the atmosphere annually. More than 90% of this emission is generated by combustion and thermochemical usage of coal, including coking. In Poland, the coking industry consumes more than 12 million Mg of bituminous coals each year. Contrary to lignites and subbituminous coals used in power plants, there is not much reliable data on mercury content in bituminous coals. The purpose of this paper was to determine mercury content in bituminous coals delivered to Polish coke plants and to analyze possible removal of mercury during coal cleaning processes. 82 samples from 9 mines were analyzed. The average mercury content varied from 28.4 to 182.6 μg kg-1 with mean value of 75.9 μg kg-1. The analysis of mercury content in three coals treated by (i) flotation, (ii) dense-media washing, and (iii) jig washer cleaning, revealed that mercury content in relation to net calorific value can be reduced by 27% (flotation) to 71% (dense-media washing). In addition, distribution of mercury, ash, and sulfur between products and rejects in the process of coal cleaning was determined. For this purpose samples of raw coals, clean coals, middling products and rejects derived from six coal preparation plants were examined (67 samples). The publication presents the mercury balance results for bituminous coal coking. The mercury is transferred to coal tar (75%, mean mercury content 2 007 μg kg-1), coke (6%, 7.5 μg kg-1), sulfur (2%, 2 998 μg kg-1) and purified coke oven gas (3%,7.5 μg m 3). Balance data shows that almost 14% of mercury is emitted to the atmosphere during the process of filling the coke oven chambers with coal.
Longitudinal Study of Wastewater Greases and Their Potential for Production of Biofuels Energy Fuels (IF 3.091) Pub Date : 2018-01-11 Megan E Hums, Hiral Amin, Ya-Chi Tsao, Mira Olson, Sabrina Spatari, Richard Cairncross
Grease trap waste (GTW) and sewage scum grease (SSG) are underutilized, high-lipid waste streams that have the potential to be converted into biodiesel. This paper presents a longitudinal study of GTW and SSG samples that were obtained over a one year period; GTW was sampled from a storage tank at a grease collection company and SSG was sampled from scum concentration buildings at three wastewater resource recovery facilities. Samples were fractionated to quantify their lipids, secondary wastewater, and solids content. Results show that the average lipid content of SSG was seasonally dependent; lipid content was 15-40% in cooler months and 3-21% in warmer months. Alternatively, GTW showed an average overall lipid content of 4% in raw GTW; however, the floating layer from settled GTW had an average lipid content of 34%. These greases could serve as feedstocks for urban low-carbon biodiesel production while reducing the volume of biosolid waste disposal.
Decomposition of Cellulose in Hot-Compressed Water: Detailed Analysis of the Products and Effect of Operating Conditions Energy Fuels (IF 3.091) Pub Date : 2018-01-10 Felipe Buendia-Kandia, Guillain Mauviel, Emmanuel Guedon, Emmanuel Rondags, Dominique Petitjean, Anthony Dufour
Understanding the reaction pathways of cellulose hydrolysis in hot-compressed water (HCW) is crucial for the optimization of fermentable sugar and chemical production. Advanced analytical strategies are required to better assess the wide range of products from cellulose conversion in HCW. In this work, cellulose conversion in HCW was conducted in an autoclave with sampling upon the reaction time under isothermal conditions (180, 220, and 260 °C from 0 to 120 min). Total water-soluble carbohydrates were quantified (phenol/sulfuric acid method). These products were first characterized by size-exclusion chromatography coupled to evaporative light scattering detection and mass spectrometry (SEC–ELSD–MS). SEC is useful for screening the molecular weight distribution of soluble products. Then, the chemical structure of water solubles has been attributed by hydrophilic interaction liquid chromatography coupled to a linear trap quadrupole Orbitrap mass spectrometer (HILIC–LTQ–Orbitrap–MS). This method notably provides evidence of the formation of a cellobiose conformer under some HCW conditions. A specific high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC–PAD) method has been developed. This method allows for a selective separation of 5-hydroxymethylfurfural (5-HMF), glucose, fructose, mannose, and oligomers up to cellopentaose. Carboxylic acids were quantified by high-performance liquid chromatography with ultraviolet detection (HPLC–UV). Solid residues obtained after HCW conversion were characterized by X-ray diffraction (XRD) and permanent gas by micro-gas chromatography. The global reaction mechanism of cellulose liquefaction in HCW is rationalized on the basis of these complementary methods. Cellulose conversion first proceeds with heterogeneous hydrolysis (fiber surface) to produce soluble oligomers in competition with pyrolysis (inner fibers with limited mass transfer of water), producing levoglucosan (promoted at a higher temperature). Soluble oligomers produce glucose and isomers by homogeneous hydrolysis (liquid phase). C6 sugars can then undergo further conversion to produce notably 5-HMF and erythrose.
Effect of acetic acid addition on decomposition of xylose in supercritical water Energy Fuels (IF 3.091) Pub Date : 2018-01-10 Tanawan Chalermsaktrakul, Yukihiko Matsumura
The supercritical water gasification of xylose, a model substrate for hemicellulose, was carried out at 400 and 450 °C and at a constant pressure of 25 MPa in the presence of acetic acid using a continuous flow reactor. More specifically, we aimed to compare the reaction rate constants of xylose decomposition both in the presence and absence of acetic acid. Upon the application of a residence time of 0.5–5 s, a xylose concentration of 1.5 wt%, and an acetic acid concentration of 1.5 wt%, we successfully elucidated the effect of acetic acid on each reaction within the reaction network for the first time. In the presence of acetic acid, the retro-aldol reactions and carbon gasification production (i.e., the radical reactions) were suppressed, while the acetic acid-catalyzed dehydration of xylulose to furfural (i.e., an ionic reaction) was enhanced by two orders of magnitude. As such, reaction control through the addition of chemical species to either stabilize ions or react with radicals appears possible.
Practical application of reservoir geochemistry in petroleum exploration: a case study from a Paleozoic carbonate reservoir in the Tarim Basin (NW China) Energy Fuels (IF 3.091) Pub Date : 2018-01-10 Meijun Li, Tie-Guan Wang, Zhongyao Xiao, Ronghui Fang, Zhiyong Ni, Weilong Deng, Youjun Tang, Chunming Zhang, Lu Yang
Reservoir geochemistry has a practical application in petroleum exploration. A typical Paleozoic carbonate oilfield was selected from the Tabei Uplift of the Tarim Basin (NW China) to exhibit the method, application and exploration implications of reservoir geochemistry. Oil-oil correlation indicates that all oils analyzed in this study belong to one single oil group. The overall oil migration direction traced by selected organic molecular markers is from the south to the north region of the Halahatang region. The source kitchen for current oil accumulations in the carbonate reservoir is predicted to locate to the south of this oilfield, most likely between the Awati and Manjiaer depressions. Based on the characteristics of hydrocarbon-bearing inclusions and the histograms of the homogenization temperatures (Th) and ice-melting temperatures of associated aqueous inclusions, the oil charging temperatures were obtained. The stratigraphic-burial and geothermal histories for representative individual well were reconstructed using 1-D basin modeling. We concluded that the Paleozoic oil reservoir has been charged twice during its oil charging history; firstly from 419 Ma to 410 Ma and secondly from 16 Ma to 8 Ma. The preservation condition for early filling oil accumulations and the mixture of oils charged during the two filling phases have controlled the density and chemical compositions of present oil accumulations. The filling points and preferential pathway indicated by isopleth maps of molecular geochemical indicators are highly indicative of oil reservoirs with high yields. It is concluded that reservoir geochemistry can be utilized, not only to determine oil migration direction and to predict the location of source kitchens, but also favorable charging pathway and potentially prolific prospecting zones. This study suggests that traps in the southern region along the preferred oil charging pathway into the Halahatang Oilfield could be the most favorable targets for further oil exploration in this region.
Organic Geochemistry and Depositional Environment of the Oltu Gemstone (Coal) in the Erzurum Area, NE Anatolia, Turkey Energy Fuels (IF 3.091) Pub Date : 2018-01-10 Reyhan Kara-Gülbay, Sadettin Korkmaz, Gülten Yaylali-Abanuz, Mert Samet Erdoğan
The Oltu gemstone exposed on southern flanks of Dutlu mountain at north of Oltu town in Erzurum city is a low rank coal. The Oltu gemstone is found as lenticular forms with thickness not exceeding cm size and lateral continuity of a few meters within the Liassic-Lower Malm Olurdere Formation consisting chiefly of claystone, sandstone and volcanics. Coals that are operated as Oltu gemstone are represented by very high TOC (67.39-78.56% wt.), high hydrogen index (HI) values (314-379 mgHC/gTOC) and very low oxygen index (OI) values (1-3 mgCO2/gTOC). Low Pr/Ph ratios indicate that coals were preserved from oxidation and deposited under anoxic conditions. In Oltu gemstone samples C29 dominates over C27 and C28 steranes. In general, high (C19+C20)/C23 tricyclic terpane, low Ts/(Ts+Tm), diasterane/sterane and C31R/C30 hopane ratios were recorded. C29 MA steroids dominate with respect to others and C29/(C28+C29) MA ratio is mostly high. DBT/P ratio of Oltu gemstone samples shows low values. Tmax values of Oltu gemstone samples (between 416-436 ºC) reflect immature-early mature character. 22S/(22R+22S) homohopane, 20S/(20R+20S) and ββ/(αα+ββ) sterane ratios and low moretane/hopane ratios, relatively high C28-TA/(C29-MA+C28-TA), MA(I)/MA(I+II), TA(I)/TA(I+II), MPI-3 (β/α MP) and MDR ratios indicate early mature character for the Oltu gemstone samples.
Impact of Oil Composition on Microwave Heating Behavior of Heavy Oils Energy Fuels (IF 3.091) Pub Date : 2018-01-10 Yang Zhang, Mohamed Adam, Abarasi Hart, Joseph Wood, Sean P Rigby, John P Robinson
Electromagnetic heating techniques have recently received significant attention as alternatives to conventional heating methods for thermal processing of viscous and heavy oils. One of the benefits of electromagnetic heating is that the electromagnetic field can penetrate the viscous oil and the rock matrix, allowing heating to take place a significant distance away from the electromagnetic source. Opportunities exist for electromagnetic heating in overcoming the heat-transfer limitations within viscous oils, and potentially as a down-hole or in-situ heating technique to raise the temperature within a reservoir. The fundamental interaction of electromagnetic energy with viscous and heavy oils and their constituent components is poorly-understood, and this study enhances the understanding of these interactions at microwave frequencies by establishing the effect of temperature on the dielectric properties of heavy oil and its SARA fractions. The dielectric properties of two heavy oils were studied at temperatures up to 300 °C and frequencies from 900 MHz to 3.0 GHz. The loss factor of both oils was found to increase significantly with temperature, which was linked to a corresponding reduction in viscosity. It is shown for the first time, contrary to previous assertions in the literature, that aromatics and resins are the main contributors towards dielectric loss in heavy oils, whereas saturates and asphaltenes were found to have a negligible influence on the loss factor of the oil. Thus, it will be seen that, at higher temperatures or where there is a high abundance of aromatics and resins, the oils are more susceptible to being heated directly with microwaves, opening up new opportunities for microwave processing of oils in refinery and field settings without a need for microwave-absorbing additives.
Sulfur and Total Carboxylic Acid Number Determination in Vacuum Gas Oil by Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy Energy Fuels (IF 3.091) Pub Date : 2018-01-10 Ramachandra Chakravarthy, Manjula Paramati, Anilkumar Savalia, Anurag Verma, Asit Kumar Das, Chandra Saravanan, Kalagouda B. Gudasi
Sulfur removal is one of the key functions of vacuum gas oil (VGO) hydrotreating reactors. Knowing feed and product properties real-time or near real-time improves reactor operations. VGO section of crude distillation unit is also prone to severe high-temperature sulfidic and naphthenic acid corrosion. In this article, we evaluate a single reflectance Attenuated Total Reflectance Fourier transform infrared (ATR-FTIR) spectroscopy as a possible quick and cost effective methodology to determine Total Carboxylic Acid Number (TCAN) and total sulfur content of VGO. The study shows that single reflectance diamond ATR crystal methodology has the right signal-to-noise ratio to accurately predict TCAN and total sulfur within the primary method’s repeatability. Statistical models have been developed using 64 sample sets of vacuum gas oil and out of which 10 samples were used for cross validation of the model. The range of TCAN in VGO samples used in this study was between 0.37 and 13.8 mg KOH per gram and Sulfur content was between 0.8 to 5.4 percent by mass. Models have been evaluated by determining correlation coefficient (R2), linearity curves obtained by plotting measured versus predicted values, and the errors associated with the prediction and cross-validation. The models showed the correlation coefficient of 0.9991for TCAN and 0.9974 for total sulfur between reference and the measured values for calibration set of samples. A root-mean-square error of calibration (RMSEC) and prediction (RMSEP) for TCAN were found to be 0.0903 and 0.0885 mg KOH per gram. Similarly, RMSEC and RMSEP values for sulfur content were 0.0829 and 0.107 percent by mass respectively. The proposed methodology for the prediction of total sulfur and TCAN is fast, efficient, cost effective and has several advantages over the standard methods recommended by UOP and American Society for testing and Materials (ASTM).
Heat-Generating Expandable Foamed Gel Used for Water Plugging in Low-Temperature Oil Reservoirs Energy Fuels (IF 3.091) Pub Date : 2018-01-10 Ning Qi, Boyang Li, Guobin Chen, Chong Liang, Xinghua Ren, Mengfei Gao
Polymers are often used for chemical water plugging. When the reservoir temperature is lower than 50 °C, the reaction between polymers and cross-linking agents is very slow, which extensively prolongs the gelation time and even leads to unsuccessful gelation. To overcome such problems, a foamed-gel system that is capable of spontaneous in situ heat generation was developed. The optimal system was identified through the orthogonal test using the gel strength, gelation time, and gel volume as indexes. The test shows that, when the ambient temperature is fixed at 30 °C and the pH value is 6.8, the system performs well. Under such circumstances, the gelation time is 40 h, the gel strength reaches the G grade, and the volumetric expansion ratio at 10 MPa exceeds 130%. Nuclear-magnetic-resonance-based T2 spectra indicate that the foamed gel injected into the rock can effectively plug large pores and, therefore, offset the heterogeneity. It is also found that the foamed gel has great capacity for volumetric expansion-based water plugging. The synchronization between gelation and gas generation is the key to the heat-generating foamed gel. Experiments suggest the properties of the developed heat-generating expandable foamed gel can be manipulated by adjusting pH values to satisfy varied requirements for placement in different reservoirs.
Experimental Study of the Polytropic Coefficient for an Air-Cooled, High-Compression-Ratio, Spark-Ignition Engine Fueled with Natural Gas, Biogas, and a Propane–Syngas Blend Energy Fuels (IF 3.091) Pub Date : 2018-01-10 Sebastián H. Quintana, Edisson S. Castaño-Mesa, Iván D. Bedoya
The polytropic coefficient is an important variable for determining errors in pressure and volume measurements and for apparent heat release calculation in engine combustion analysis. For commercial gasoline-fueled spark-ignition engines and diesel-fueled compression-ignition engines, a wide understanding about the thermodynamic models and values of the polytropic coefficient exists; however, in other technologies, in which gaseous fuels are used, the pressure treatment strategies and heat transfer models should be adjusted to allow for a better calculation of the polytropic coefficient. This paper presents research on the effects of fuel composition, spark timing, and engine load on the polytropic coefficient in an air-cooled, spark-ignition engine with a high compression ratio (15.5:1). The fuels tested were natural gas, biogas, and a propane–syngas blend. The experimental results suggest that, during compression, the appropriate crank angle interval for polytropic coefficient estimation is between 50 and 30 crank angle degree (CAD) before top dead center (BTDC), and during expansion, the appropriate crank angle interval is between 40 and 60 CAD after top dead center (ATDC). It was found that the polytropic coefficient is lowered during compression and increased during expansion with advanced spark timings. Cycle–cycle variations tend to increase the polytropic coefficient during compression and reduce it during expansion.
Production of Synthetic Fischer–Tropsch Diesel from Renewables: Thermoeconomic and Environmental Analysis Energy Fuels (IF 3.091) Pub Date : 2018-01-09 Mahrokh Samavati, Massimo Santarelli, Andrew Martin, Vera Nemanova
In this study, a novel integrated system for production of advanced synthetic diesel is proposed and analyzed from thermodynamic, economic, and environmental perspectives. This system consists of a solid oxide electrolyzer, entrained gasification, a Fischer–Tropsch reactor (FT), and upgrading processes. Eleven different combinations of precursor syngas production through steam and CO2 co-electrolysis and biomass gasification are investigated. Results show that an increasing share of produced syngas in the electrolyzer unit results in higher system efficiencies, emission savings, and levelized cost of FT diesel. Moreover, different options of heat and mass flow recovery are considered. It is concluded that recovery of produced medium pressure steam in the system is highly beneficial and recommended. Besides, it is shown that while oxygen recovery is the best choice of mass recovery, hydrogen recovery for internal use has adverse effect on the system performance.
Release and Transformation Behaviors of Sodium, Calcium, and Iron during Oxy-fuel Combustion of Zhundong Coals Energy Fuels (IF 3.091) Pub Date : 2018-01-09 Chang’an Wang, Lei Zhao, Tao Han, Wufeng Chen, Yu Yan, Xi Jin, Defu Che
Zhundong coal has attracted an increasing concern due to its super huge reserve but high content of alkali metals. Oxy-fuel combustion of Zhundong coal benefits the near-zero emission of pollutants in coal-fired power plants and promotes the large-scale utilization of high-alkali coal. However, few efforts if any have been conducted on oxy-fuel combustion of Zhundong coal. The previous studies related to Zhundong coal were mainly focused on sodium behaviors but little work has been performed on calcium and iron, while calcium and iron are very likely to generate significant influences on fouling problems in combustion of Zhundong coal. The present study aimed to elucidate the release and transformation behaviors of sodium, calcium, and iron in oxy-fuel combustion of Zhundong coal using a fixed-bed reactor. Experimental results indicated that calcium in Zhundong coal was mainly present as the ammonium acetate-soluble form, while the iron existed in forms of hydrochloric acid-soluble and insoluble. With the increasing combustion temperature, the ash yields of Zhundong coals decreased and the volatilization ratio of sodium increased, while the temperature had a weak influence on ash yield and the release of water-soluble sodium between 800 and 1000 °C. The variations of total calcium with combustion temperature were not significant, but transformations among various chemical forms occurred. The decreased iron of the hydrochloric acid-soluble form was transformed into the insoluble form and discharged into gaseous phase. Compared to the air case, oxy-fuel combustion with 21% oxygen led to more sodium and iron retained in residual ash, while it promoted the release of calcium. The mineral transformation and ash formation were susceptible to the high content of carbon dioxide under oxy-fuel condition and were strongly associated with the chemical forms of sodium, calcium, and iron within Zhundong coals. The crystalline mineral species in Zhundong ash were obviously influenced by the combustion temperature and partly affected by the atmosphere. The differences of mineral species of Zhundong ash between air and oxy-fuel cases were mainly present in the range of 800–1000 °C, which was closely related to the decomposition of calcite and transformation of calcium. The oxygen content dependency of transformation behaviors of sodium, calcium, and iron was greatly different during oxy-fuel combustion. This work possibly offered an improved understanding of the functional mechanisms of sodium, calcium, and iron on fouling issues.
Enhanced CO2 Adsorption on Nitrogen-Doped Porous Carbons Derived from Commercial Phenolic Resin Energy Fuels (IF 3.091) Pub Date : 2018-01-09 Limin Yue, Linli Rao, Linlin Wang, Yan Sun, Zhenzhen Wu, Herbert DaCosta, Xin Hu
The CO2-capture potential of porous carbons that have been derived from phenolic resin and doped with nitrogen was assessed in this work. Using carbonized commercial phenolic resin as carbon precursors, a series of carbons have been synthesized using urea modification and KOH activation under different conditions. The activation temperature and mass ratio of KOH to precursor affected the CO2 uptake capacity. These phenolic-resin-derived carbons show high CO2 capture capacity, up to 4.61 mmol/g at 25 °C and 7.13 mmol/g at 0 °C under atmospheric pressure. The sample prepared under relatively mild conditions, i.e., activation temperature of 600 °C and mass KOH/precursor of 3, demonstrated the maximum CO2 uptake capacity under ambient conditions. A systematic study shows that the synergetic effects of narrow microporosity and nitrogen content determine the sorbents’ capability to capture CO2. In addition, the pore size and the narrow micropores’ distribution affect the CO2 adsorption capacity of this series of porous carbons. Moreover, these resin-derived carbons show other superior CO2 capture properties such as fast sorption kinetics, high CO2/N2 selectivity, moderate heat of adsorption, stable recyclability, and high dynamic CO2 capture capacity.
In Situ Analysis of Catalytic Effect of Calcium Nitrate on Shenmu Coal Pyrolysis with Pyrolysis Vacuum Ultraviolet Photoionization Mass Spectrometry Energy Fuels (IF 3.091) Pub Date : 2018-01-10 Zhou Yang, Gang Li, Lijun Jin, Jian Zhou, Jiaofei Wang, Yang Li, Haoquan Hu
To investigate the effect of calcium mineral on the product distribution of low rank coal pyrolysis, a Chinese subbituminous coal (Shenmu coal), and its additive samples with 5% and 10% calcium contents, were selected to study with a homemade pyrolysis vacuum ultraviolet photoionization mass spectrometry (Py-VUV-PIMS). In this system, secondary reactions of the pyrolysis products were generally inhibited because of in situ sampling, soft ionization, and high vacuum environment, which allowed the direct detection of the initial pyrolytic products. Most evolved compounds during temperature programmed heating from 30 to 650 °C were ionized by a VUV lamp (10.6 eV). The main products include five categories: alkenes, dienes, aromatics, phenols, and dihydroxy aromatics, which were formed via the homolytic scission of weak bonds in side chains and bridges between aromatic nuclei in coal structure. The calcium mineral additives can dramatically affect pyrolytic product distribution, especially oxygen-containing compounds. The main reason is that calcium mineral plays a catalytic role of deoxygenation, which prompted oxygen-containing compounds into corresponding aromatics, and resulted in the product of BTX levels increase significantly. The decrease of relative average molecular weight indicated the conversion of heavier components into lighter species, in terms of the observed m/z of the evolved gas components.
DOSY-NMR AS AN ALTERNATIVE TECHNIQUE TO IMPROVE ASPHALTENES CHARACTERIZATION Energy Fuels (IF 3.091) Pub Date : 2018-01-10 Luiz Silvino Chinelatto Júnior, Sonia M. Cabral de Menezes, Hercílio de Angeli Honorato, Marcia Cristina Khalil de Oliveira, Luiz Carlos do C. Marques
An asphaltene sample from a Light Arabian crude oil was characterized using several analytical techniques such as TGA, NMR, FTIR and elemental analysis. The results showed that the sample has a high sulfur content, highly condensed aromatic compounds, and the average molecular structure is predominantly of continental/island type, but the presence of significant amount of methylene carbons in long alkyl chains is clear. A DOSY NMR experiment was carried out to detect the presence of asphaltene aggregates, evaluate their size and shed light on the presence of maltenic occluded species and entrained residual solvent. In the DOSY spectrum some sample signals were attributed to non-asphaltenic molecules showing that it is possible to achieve key features of the sample complexity in “one shot”.
Estimation of Static Dissipater Additives (SDA) in Aviation Turbine Fuels (ATF) using ASTM D 7524 and ASTM D2624; Observation, Precautions and Suggestion thereof. Energy Fuels (IF 3.091) Pub Date : 2018-01-10 Anil Yadav, Maya Chakradhar, Anju Chopra, Jayaraj Christopher, Gurpreet Singh Kapur
Static Dissipater Additives (SDA) is conductivity improver additives that are added to ATF to avoid sudden increase in conductivity that may occur during transfer/pumping of ATF. STADIS 450 has been used globally as the SDA in aviation jet A1. The dosage of SDA into jet fuels is very closely specified (1-3 ppm). Due to surface active nature, SDA dosage may deplete with time. The monitoring of concentration of SDA is very critical and is generally carried out using conductivity measurement as per ASTM D2624 or as per liquid chromatographic technique based ASTM D7524 method that provides for “Determination of Static Dissipater Additive (SDA) in Aviation turbine fuel using HPLC technique with UV detector in the range of 1 to 12 ppm”. In this work SDA blended ATF in range of 1 to 5 ppm have been analyzed for estimation of SDA using both HPLC based ASTM D7524 and conductivity measurement based ASTM D2624. This paper suggests precautions that need to be taken while using two methods. The work also recommends suggestions that can make the ASTM D 7524 findings more specific, precise and ensures better recoveries. While the initial procedure were adopted from ASTM D7524, multiple collections during cartridge extraction process and use of HPLC with Photodiode detector instead of UV detector bring down the detection level to 0.5 ppm SDA in ATF.
Interpretation of NMR Relaxation in Bitumen and Organic Shale using Polymer-Heptane Mixes Energy Fuels (IF 3.091) Pub Date : 2018-01-10 Philip M. Singer, Zeliang Chen, Lawrence B. Alemany, George J Hirasaki, Kairan Zhu, Harry Xie, Tuan D. Vo
One of the much debated mysteries in 1H NMR relaxation measurements of bitumen and heavy crude-oils is the departure from expected theoretical trends at high viscosities, where traditional theories of 1H-1H dipole-dipole interactions predict an increase in T1 with increasing viscosity. However, previous experiments on bitumen and heavy crude-oils clearly show that T1LM (i.e. log-mean of the T1 distribution) becomes independent of viscosity at high viscosities; in other words, T1LM versus viscosity approaches a plateau. We report 1H NMR data at ambient conditions on a set of pure polymers and polymer-heptane mixes spanning a wide range of viscosities (η = 0.39 cP ↔ 334,000 cP) and NMR frequencies (ω0/2π = f0 = 2.3 MHz ↔ 400 MHz), and find that at high viscosities (i.e. in the slow-motion regime) T1LM plateaus to a value T1LM> ∝ ω0 independent of viscosity, similar to bitumen. More specifically, on a frequency-normalized scale, we find that T1LM> × 2.3/f0 = 3 ms (i.e. normalized relative to 2.3 MHz), in good agreement with bitumen and previously reported polymers. Our findings suggest that in the high-viscosity limit, T1LM> and T2LM> for polymers, bitumen and heavy crude-oils can be explained by 1H-1H dipole-dipole interactions, without the need to invoke surface paramagnetism. In light of this, we propose a new relaxation model to account for the viscosity and frequency dependences of T1LM and T2LM, solely based on 1H-1H dipole-dipole interactions. We also determine the surface relaxation components T1S and T2S of heptane in the polymer-heptane mixes, where the polymer acts as the “surface” for heptane. We report ratios up to T1S /T2S = 4 and dispersion T1S (ω0) for heptane in the mix, similar to previously reported data for hydrocarbons confined in organic matter such as bitumen and kerogen. These findings imply that 1H-1H dipole-dipole interactions enhanced by nano-pore confinement dominate T1S and T2S relaxation in saturated organic-rich shales.
Fluid-Solid Coupling Characteristics of Gas-Bearing Coal Subject to Hydraulic Slotting: An Experimental Investigation Energy Fuels (IF 3.091) Pub Date : 2018-01-09 Quanle Zou, Baiquan Lin
Chinese coal seams are characterized by high gas content and low permeability. The permeability of coal seams should be improved to achieve maximum extraction of coalbed methane. This study explores how coal and gas behave when subjected to hydraulic slotting. A fluid–solid coupling experimental system of gas-bearing coal subjected to hydraulic slotting was first established. Then, the fluid–solid coupling property of gas-bearing coal subjected to hydraulic slotting was revealed using the established experimental system. Meanwhile, indicators used to describe the process of hydraulic slotting were derived, and the influencing factors affecting the process of hydraulic slotting were analyzed using the aforementioned indicators. The research achievements indicate that the gas pressure response of the monitoring points in the coal sample shows different characteristics at different stages. Corresponding to the change trend of the gas pressure, the vertical and parallel strains demonstrate the five-stage change characteristics. With the increase of gas pressure, the final deformation amount before slotting gradually increases, and the gas diffusion parameter increases exponentially. With the increase of the slot radius, the gas diffusion parameter shows a similar change tendency with the ultimate deformation amount, i.e., it tends to become flat after a rapid increase. The research achievements can provide certain theoretical and practical references for the reveal of the enhanced coalbed methane recovery mechanism through hydraulic slotting and the rational selection of the key parameters in the field test, respectively.
In-cylinder Combustion and Soot Evolution in the Transition from Conventional CI mode to PPC Energy Fuels (IF 3.091) Pub Date : 2018-01-09 Yanzhao An, Mohammed Jaasim Mubarak Ali, Vallinayagam Raman, Hong G Im, Bengt Johansson
The present study intends to explore the in-cylinder combustion and evolution of soot emission during the transition from conventional compression ignition (CI) combustion to partially premixed combustion (PPC) at low load conditions. In-cylinder combustion images and engine-out emissions were measured in an optical engine fueled with low octane heavy naphtha fuel (RON = 50). Full cycle engine simulations were performed using a three-dimensional computational fluid dynamics code CONVERGETM, coupled with gas phase chemical kinetics, turbulence, and particulate size mimic soot model. The simulations were performed under low load conditions (IMEP ~ 2 to 3 bar) at an engine speed of 1200 rpm. The start of injection (SOI) was advanced from late (-10 CAD aTDC) to early fuel injection timings (-40 CAD aTDC) to realize the combustion transition from CI combustion to PPC. The simulation results of combustion and emission are compared with the experimental results at both CI and PPC combustion modes. The results of the study show a typical low-temperature stratified lean combustion at PPC mode, while high-temperature spray-driven combustion is evident at CI mode. The in-cylinder small intermediates species such as acetylene (C2H2), propargyl (C3H3), cyclopentadienyl (C5H5) and polycyclic aromatic hydrocarbons (PAHs) were significantly suppressed at PPC mode. Nucleation reaction of PAHs collision contributed to main soot mass production. The distribution of soot mass and particle number density was consistent with the distribution of high-temperature zones at CI and PPC combustion modes.
Could ASCI be used as the "WAT" of Asphaltenes ? Illustration Through the Study of the Polydispersity of PetroPhase 2017 Asphaltenes Energy Fuels (IF 3.091) Pub Date : 2018-01-09 Nicolas Passade-Boupat, Jean-Philippe Gingras, Carole Desplobins, Honggang Zhou
Being able to assess the solubility properties of asphaltenes is essential for oilfield asphaltene risk assessment. The solubility distribution of the PetroPhase 2017 Asphaltenes was characterized using the Asphaltene Solubility Class Index (ASCI) which a simple methodology based on precipitation onset determination in different Heptols. This ASCI method was also used to measure the polydispersity in terms of solubility for PetroPhase 2017 Asphaltenes that were fractionated from the native crude oil with precipitants of different qualities. Similarly to other crude oils, asphaltenes from the Petrophase 2017 have high level of polydispersity ranging from fractions “insoluble in Toluene” to “soluble in Heptane” which may seem contradictory with usual definition of asphaltenes. The modification of the precipitant-to-crude oil ratio, with heptane as precipitant, also highlighted the presence co-precipitated materials that did not affect the solubility class of asphaltenes. From our experience over the last fifteen years, using ASCI or another equivalent tool , would greatly improve the comparison between different studies on asphaltene, similarly to the well-known Wax Appearance Temperature which is measured and reported in in the vast majority of studies on paraffins.
Methyl Linoleate and Methyl Oleate Bond Dissociation Energies: Electronic Structure Fishing for Wise Crack Products Energy Fuels (IF 3.091) Pub Date : 2018-01-09 Zachary R. Wilson, Matthew R Siebert
The world depends on petroleum for everything from the plastics that contain our food, to the natural gas that heats our homes, to the gasoline that feed our cars’ engines. With rising prices of petroleum reflecting demand for this finite resource, attention has been turned to alternative sources of energy. Biodiesel, which exhibits many of the same properties as conventional diesel but is derived from biological sources, is an attractive alternative. Fats and oils are converted to biodiesel, fatty acid methyl esters (FAMEs), by transesterification. FAMEs are subsequently thermally cracked to form more light-weight transportation fuels such as natural gas, kerosene, and possibly gasoline. We aim to further understand the thermal cracking procedure, at an atomic-level, in hopes that this may aid in future engineering of viable fuels. We will present our study on the effective computational modeling of bond dissociations in the FAMEs methyl linoleate and methyl oleate, which are the most common biodiesel product of soybeans and rapeseeds (also known as canola seeds). We have employed quantum chemical methods, including: the density functionals B3LYP, M06-2X, and B97D; the wavefunction-based MP2; and the composite CBS-QB3 method. Bond dissociation in a 44-reaction database set for which experimental energies are known are used to evaluate methods. We find that the M06-2X/6-31+G(d,p) model chemistry provides results comparable to the composite CBS-QB3 method at a much reduced cost. Lastly, data are compiled for possible bond dissociations in FAMEs methyl oleate and methyl linoleate.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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