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  • Asphaltene Deposition Preference and Permeability Reduction Mechanisms in Oil Reservoirs: Evidence from Combining X-ray Microtomography with Fluorescence Microscopy
    Energy Fuels (IF 3.091) Pub Date : 2017-09-19
    Xiao Feng, Jianhui Zeng, Yong Ma, Kaiyu Jia, Juncheng Qiao, Yongchao Zhang, Sen Feng

    Asphaltene deposition in oil reservoirs during acid stimulation, natural depletion, and CO2 injection may cause intense formation damage and reduced productivity. Gaining a better understanding of the asphaltene deposition mechanisms and their influence on the reservoir permeability reduction will contribute to the prevention of reservoir damage and the optimization of development schemes. Although numerous models and experiments have been applied to simulate the asphaltene deposition process and evaluate the reservoir permeability loss, few analyses have been performed on natural samples from oil reservoirs undergoing asphaltene deposition. Moreover, permeability reduction simulation due to asphaltene deposition has not yet been performed in three-dimensional (3D) microscale pore systems. In this work, sandstone samples were collected from natural oil reservoirs with asphaltene deposition and analyzed by both X-ray tomography and fluorescence microscopy to identify the asphaltene. A Navier–Stokes simulator and pore network model are used to study the 3D pore spaces and to calculate the permeabilities and pore radius distributions. Ideal asphaltene deposition models are applied in the 3D pore spaces to simulate the influences of surface adsorption and pore blockage on the permeability reduction. By comparing the calculation results of the ideal models and natural samples, we found that the asphaltene deposition is a coupled effect of the surface adsorption and the pore blockage, which causes a weaker permeability loss than that from the ideal single factor models.

    更新日期:2017-09-20
  • Catalytic Hydrodeoxygenation of Guaiacol over Palladium Catalyst on Different Titania Supports
    Energy Fuels (IF 3.091) Pub Date : 2017-09-19
    Mohong Lu, Hu Du, Bin Wei, Jie Zhu, Mingshi Li, Yuhua Shan, Chunshan Song

    Pd catalysts supported on TiO2 with different crystalline phases were prepared with formaldehyde as reducing agent and examined for hydrodeoxygenation (HDO) of guaiacol. Their properties were characterized by N2 adsorption, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. Compared to the carbon-supported Pd catalysts, TiO2-supported Pd catalysts exhibited higher C–O bond scission ability, which may be attributed to the presence of partially reduced titanium species originating from the reduction of Ti4+ by spillover hydrogen from Pd at 200 °C on the surface of TiO2. Guaiacol was hydrogenated on Pd sites to give 2-methoxycyclohexanol, which diffused to partially reduced titanium species and subsequently reacted with hydrogen from Pd to generate cyclohexane. Anatase TiO2-supported Pd catalyst gave the highest HDO activity of guaiacol among the Pd catalysts supported on three types of TiO2 (anatase, rutile, and their mix, P25), suggesting that more partially reduced titanium species are in favor of the HDO reaction because anatase is facile to reduce by H2 at 200 °C. Higher selectivity of cyclohexane for Pd/TiO2 reduced at 500 °C than that reduced at 200 °C further confirmed that the enhanced C–O bond scission ability of Pd/TiO2 is mainly attributed to the partially reduced titanium species on the surface of TiO2.

    更新日期:2017-09-20
  • Comparative Research about Wheat Straw Lignin from the Black Liquor after Soda-Oxygen and Soda-AQ Pulping: Structural Changes and Pyrolysis Behavior
    Energy Fuels (IF 3.091) Pub Date : 2017-09-19
    Lilong Zhang, Keli Chen, Lincai Peng

    Structural changes and pyrolysis behavior of lignins derived from black liquor of soda-anthraquinone (SAL) and soda-oxygen pulping (SOL) for wheat straw at similar delignification rates have been investigated. The lignin was first isolated through acid precipitation and then was characterized by various analytical techniques, including elemental analysis, gel permeation chromatography, Fourier transform infrared spectroscopy,13C–1H heteronuclear single quantum correlation spectra analysis, and thermogravimetry mass spectrometry. At similar delignification rates, the pulping process for gaining quality pulp, SOL contained more (β-O-4) structure and hydroxyl and carbonyl groups, which provided promising results for depolymerization and pyrolysis. SOL showed superior pyrolysis properties including higher combustibility gas formation and lower pyrolysis temperature. Small group organic products like acetic acid and furural could be released from SOL at 100 °C lower temperature, while more methane could be produced in a larger temperature range.

    更新日期:2017-09-20
  • Air-Blown Entrained-Flow Gasification of Biomass: Influence of Operating Conditions on Tar Generation
    Energy Fuels (IF 3.091) Pub Date : 2017-09-19
    Ludwig Briesemeister, Michael Kremling, Sebastian Fendt, Hartmut Spliethoff

    The formation of tars in gasifiers based on fluidized- or fixed-bed technology is a major problem in biomass gasification. By pretreating biomass using hydrothermal carbonization (HTC), entrained-flow gasification becomes applicable. Oxygen-blown entrained-flow gasifiers (EFGs) operate at very high process temperatures, leading to an almost tar-free syngas. However, in decentralized small-scale units, preferably air is used as the gasification agent, which, in turn, causes lower gasifier temperatures. The specific impacts of air-blown gasification conditions and fuel properties of biocoal from HTC on tar formation require particular attention. Therefore, in this work, tar formation under air-blown gasification conditions is investigated using solid-phase adsorption at an electrically heated EFG with temperatures of 900–1300 °C and different air/fuel equivalence ratios λ. Furthermore, tars are measured in the hot syngas of an industrial-like autothermal EFG. HTC biocoals of various feedstocks (beech, biogenic residuals, municipal waste, and green waste), raw biomass (corn cobs), and fossil fuel (Rhenish lignite) are used as fuels. The results show that the main influencing parameter on tar loading in the syngas is the temperature, whereas the residence time and λ have less impact. However, in autothermal operation, the choice of λ controls the gasifier temperature and, thus, effectively affects the resulting tar loading. Identified tar compounds are mainly light polycyclic aromatic hydrocarbons, of which naphthalene is the most frequently occurring. At 1300 °C, tar loading is reduced to less than 0.2 g/Nm3, which allows for direct syngas use in internal combustion engines.

    更新日期:2017-09-20
  • Simultaneous Separation of H2S and CO2 from Biogas by Gas–Liquid Membrane Contactor Using Single and Mixed Absorbents
    Energy Fuels (IF 3.091) Pub Date : 2017-09-19
    Pengrui Jin, Chuan Huang, Yadong Shen, Xinyuan Zhan, Xinyue Hu, Lei Wang, Liao Wang

    The present work studied the simultaneous separation of H2S and CO2 from biogas by gas–liquid membrane contactor (GLMC) using single and mixed absorbents. The synthetic biogas contained 300 to 900 ppm of H2S, 30% to 50% CO2 and CH4. To better understand the effects of different absorbents on simultaneous separation of H2S and CO2 from biogas, water, monoethanolamine (MEA, primary amine), potassium carbonate (K2CO3, inorganic salt), potassium hydroxide (KOH, inorganic salt), and potassium sarcosine (PS, organic salt) were applied as absorbent solutions. Poly(vinylidene fluoride) (PVDF) hollow fiber membrane was used in the membrane contactor modules. The simultaneous absorption performance of CO2 and H2S into single and mixed absorbents was investigated. In addition, the effects of liquid and gas velocities, absorbent concentration, acid gas content of the feed gas, and gas pressure on the absorption performance and the analysis of mass transfer coefficients were investigated. The results indicated that the highest H2S absorption flux was obtained when KOH and K2CO3 were used as single absorbents, and the highest CO2 flux was obtained using PS as the single absorbent. The use of promoted K2CO3 with PS solutions could simultaneously improve the absorption flux of H2S and CO2. Increasing the liquid flow rate and absorbent concentration led to an increase in the CO2 absorption flux, while increasing the gas flow rate led to a significant increase in H2S absorption; The change of liquid flow rate has little effect on H2S absorption flux. A long-term stability test revealed that partial wetting of membrane could reduce the CO2 absorption flux but has little effect on H2S absorption flux. The detailed analysis of the mass transfer coefficients showed that liquid side resistance was negligible in comparison with membrane and gas side resistances for H2S absorption. On the contrary, the mass transfer process of CO2 was controlled by liquid mass transfer resistance.

    更新日期:2017-09-20
  • Analysis of the geological conditions for shale gas accumulation: two different Carboniferous marine-continental transitional facies in the Bayanhot Basin, China
    Energy Fuels (IF 3.091) Pub Date : 2017-09-19
    Hongliang Wang, Jintong Liang, Xiaohui Li, Xinyuan Ji, Qixian Zhang, Rongjie Huang

    The sedimentary environment plays a controlling role in the enrichment of the shale gas resources. Based on field data, this paper studies the characteristics of marine-continental transitional sedimentary environment in Bayanhot Basin by means of laboratory analysis, scanning electron microscope and comparative analysis. Through the comparison of shale organic geochemical characteristics and shale physical analysis between the southern and northern sedimentary environments in Bayanhot Basin, the difference analysis of shale gas enrichment conditions is undertaken. It was found that: (1)The hydrocarbon generating potential of shale in the northern delta sedimentary environment is better than the shale in the southern combined sedimentary system considering the total organic carbon rate and organic matter type; and (2) the shale in the southern Bayanhot Basin, with better shale physical micro-characteristics, is conducive to the shale in the northern part in terms of gas accumulation and fracturing operation.

    更新日期:2017-09-20
  • Two-Phase Fluidized Bed Model for Pressurized Carbonation Kinetics of Calcium Oxide
    Energy Fuels (IF 3.091) Pub Date : 2017-09-19
    Joseph Yao, Zili Zhang, Mark Sceats, Geoffrey C. Maitland, Paul S. Fennell

    A two-phase reactor model has been developed using a system of ordinary differential equations in MATLAB to model the carbonation reaction and therefore determine the kinetics of calcium oxide in a pressurised fluidised bed reactor as part of the calcium looping cycle. The model assumes that the particulate and bubble phases are modelled as a CSTR and a PFR respectively. The random pore model developed by Bhatia and Perlmutter1 is incorporated into the system of equations to predict the rate of carbonation for pressures up to 5 bara total, and CO2 partial pressures up to 150 kPa. The surface rate constant and product layer diffusivity in the random pore model expression were obtained by fitting the model to experimental data for a range of pressures, CO2 concentrations and temperatures by minimization of the resid-ual sum of squares. The surface rate constants were found to be between 3.05 and 12.9 x 10-10 m4 mol-1 s-1 for a temper-ature range of 550 to 750 °C. The product layer diffusivities were found to be between 0.06 and 23.6 x 10-13 m2 s-1 for the same temperature range. The surface rate constant and product layer diffusivity activation energy were calculated using the Arrhenius equation and was found to be approximately 48 ± 17 kJ mol-1 and 196 ± 43 kJ mol-1 respectively.

    更新日期:2017-09-20
  • Removal of HCl in flue gases by calcined limestone at high temperatures
    Energy Fuels (IF 3.091) Pub Date : 2017-09-19
    Geng-Min Lin, Chien-Song Chyang

    Experimental study of dry HCl removal from simulated combustion flue gases using calcined limestone (CaO) is reported. The study was conducted in a unique fixed-bed reactor coupled with an online Fourier transform infrared (FTIR) spectrometer to investigate the effects of the presence of SO2, CO2 and O2 on the chlorination reactivity of calcined limestone. The dechlorination efficiency, defined by the effluent HCl concentration, would be used to describe the HCl absorption history to gain a better understanding of the chlorination behavior. The experimental results indicated that the HCl uptake capacity remains less affected under various gas atmospheres at 650 °C although the chlorination is found to be faster when CO2 is present. At temperatures of 750 or 850 °C, the presence of SO2 or O2 significantly decreases the reactivity of the calcined limestone toward HCl. The concurrent sulfation of chlorides, such as CaCl2•H2O and/or CaClOH, causes the subsequent re-release of HCl to the gas phase, thus reducing the attainable extent of the chlorination reaction. The presence of O2 impedes the conversion of calcined limestone to chlorides, presumably through some type of reaction involving the dechlorination of the sorbent particles.

    更新日期:2017-09-20
  • Coarse-grained model and boiling point prediction for asphaltene model compounds via HMC-WL simulations.
    Energy Fuels (IF 3.091) Pub Date : 2017-09-19
    Caroline Desgranges, Jerome Delhommelle

    The determination of vapor-liquid equilibrium data is a key parameter for the conditions of stability or precipitation of asphaltenes. In this work, using molecular simulation, we parametrize a coarse-grained force field for a series of alkyldipyrene compounds, that are often used as model compounds for asphaltenes, and predict their thermodynamic properties at coexistence. To achieve this, we combine a Wang-Landau approach with hybrid Monte Carlo simulations in the isothermal-isobaric ensemble to sample extensively the configurations of the system over a wide range of densities. This allows us to obtain the conditions of coexistence and to shed light on the impact on the alkyl chain on the thermodynamic properties. Most notably, we identify a quasi-linear relationship between the boiling temperature of these compounds and the length of the alkyl chain.

    更新日期:2017-09-20
  • Methods to calculate hydrogen consumption during hydrocracking experiments in batch reactors
    Energy Fuels (IF 3.091) Pub Date : 2017-09-19
    Guillermo Felix, Alexander Quitian, Emmanuel Rodriguez, Jorge Ancheyta, Fernando Trejo

    Different approaches are described to quantify hydrogen consumption, gas production and mass balances in batch reactors for conducting hydrotreating experiments. The methods studied were weighting, measuring the volume of gas loaded and unloaded from the reactor (with gas syringe and with gasometer), and by calculating the gas volume with an equation of state. All of the approaches proved to be adequate with low losses of mass. Experimental data of slurry-phase hydrocracking with mineral catalyst (molybdenite and hematite) conducted in reactors of different were used to apply the different methods. Thesize of the reactor did not have a significant effect on the properties of the products, although a larger reactor size allows for a better precision in the measurement of the amount of feeds and products.

    更新日期:2017-09-20
  • Impact of Gaseous Chemistry in H2/O2/N2 Combustion over Platinum at Fuel-Lean Stoichiometries and Pressures 1.0 to 3.5 bar
    Energy Fuels (IF 3.091) Pub Date : 2017-09-19
    Ran Sui, John Mantzaras, Et-touhami Es-sebbar, Mohammad A Safi, Rolf Bombach

    The catalytic and gas-phase combustion of fuel-lean H2/O2/N2 premixtures was investigated in a channel coated with platinum at pressures 1.0-3.5 bar, a range encompassing microreactors in portable power generation systems and passive hydrogen recombiners in nuclear power plants. One-dimensional Raman spectroscopy assessed the progress of catalytic hydrogen combustion, while planar laser induced fluorescence (LIF) of the hydroxyl radical monitored gaseous combustion. Simulations were performed using a 2-D code with detailed catalytic and gas-phase reaction mechanisms and realistic transport. Both LIF measurements and simulations revealed that homogeneous combustion was vigorously sustained below ~2.5 bar, while it was effectively suppressed at higher pressures. This was due to the intricate pressure dependency of the hydrogen gaseous ignition chemistry and the competition between catalytic and gaseous chemical reactions for hydrogen consumption. Parametric simulations determined the smallest critical channel heights allowing for appreciable gaseous combustion and their dependency on pressure, wall temperature and inlet velocity. It was shown that for the narrower channels of catalytic microreactors homogeneous combustion was relevant only for wall temperatures above 1300 K, whereas for the wider hydrogen recombiner channels it could be relevant for wall temperatures down to 1100 K. Furthermore, at 1100 K the critical channel heights were non-monotonic functions of pressure, reaching their peaks at 2.0-2.5 bar.

    更新日期:2017-09-20
  • Designing moisture-swing CO2 sorbents through anion screening of polymeric ionic liquids
    Energy Fuels (IF 3.091) Pub Date : 2017-09-19
    Tao Wang, Kun Ge, Yusong Wu, Kexian Chen, Mengxiang Fang, Zhongyang Luo

    Polymeric ionic liquids (PILs) are promising CO2 sorbents as their behaviors are tunable by assembling ion pairs. This work aims to design CO2 sorbents with unique moisture-swing adsorption performance by assembling different anions on quaternary-ammonium-based PILs. Two aspects of the sorbent design were studied: the suitability of the CO2 affinity for different applications (e.g., direct air capture or flue gas capture) and capability for moisture-swing adsorption. Carbonate, fluoride and acetate were chosen as counter anions as they are representative anions with different basicity, valence and water affinity. CO2 affinity was found to positively correlate with the pKa value of the counter anion, except for fluoride, which has an intrinsic character of attracting protons. The moisture swing capacity is determined by the difference between the hydration energies of the reactant and product after CO2 adsorption and followed the order carbonate > fluoride > acetate. Further investigations revealed that the repulsion between the two quaternary ammonium cations could promote the dissociation of hydrated water, which results in the lowest activation energy for CO2 adsorption for the PIL with carbonate. Therefore, the PIL with carbonate is potentially a desirable candidate for air capture and moisture-swing regeneration, while the PIL with acetate is suitable for CO2 capture under high partial pressure and regeneration through conventional approaches. This study provides a quantitative microscopic insight into the role of the anion in CO2 adsorption and paves the way toward the optimal PIL structure for CO2 capture under specific circumstances.

    更新日期:2017-09-20
  • Novel Method of Ultralow SO2 Emission for CFB Boilers: Combination of Limestone Injection and Activated Carbon Adsorption
    Energy Fuels (IF 3.091) Pub Date : 2017-09-19
    Yan Dong, Yuzhong Li, Liqiang Zhang, Lin Cui, Bo Zhang, Yong Dong
    更新日期:2017-09-19
  • Towards the Accurate Prediction of Liquid Phase Oxidation of Aromatics - A Detailed Kinetic Mechanism for Toluene Autoxidation
    Energy Fuels (IF 3.091) Pub Date : 2017-09-19
    Detlev Conrad Mielczarek, Mickaël Matrat, Arij Ben-Amara, Yvan Bouyou, Perrine Wund, Laurie Starck

    Toluene is an important compound in the chemical industry as well as an often chosen simple surrogate compound for aromatic components in transport fuels. As a results, an improved understanding of the liquid phase oxidation of toluene is of interest to both the chemical industry but also the transportation sector. In this work, a detailed autoxidation mechanism for the liquid phase oxidation of toluene is developed using an automated mechanism generation tool. The resultant mechanism is significantly improved using quantum chemistry calculations to update the thermodynamic parameters of key species in solution. Comparisons are made between the predicted and experimentally measured induction period and the obtained mechanism. The agreement between both is found to be within one order of magnitude. Rate of production analysis and sensitivity analysis are carried out to explain and understand the reactions paths present in the mechanism. The behaviour of the mechanism is commented upon qualitatively, however no quantitative data could be obtained with the selected test method.

    更新日期:2017-09-19
  • Comparison of Acidizing and Ultrasonic Waves, and Their Synergetic Effect for the Mitigation of Inorganic Plugs
    Energy Fuels (IF 3.091) Pub Date : 2017-09-18
    Nasir Khan, Jingyang Pu, Chunsheng Pu, Xu Li, Lei Zhang, Xiaoyu Gu, Heng Zheng

    The oil and gas industry is plagued by inevitable formation damaged in the wellbore proximity during entire life of the well. Therefore, it is indispensable to ameliorate the damaged permeability by either using conventional applied techniques or ultrasonic-assisted stimulation method. The latter is characterized by efficient, simple and convenient, and environmentally secure method. Due to these distinguished characteristics, the demand of this physical Enhanced Oil Recovery (EOR) technique increased in petroleum industry. In this study, ultrasonic waves and hydrochloric acid (HCl) were used separately as well as in combination to recover the lost productivity caused by calcium carbonate (CaCO3) inorganic plugs in low permeability sandstone core samples. Results showed that permeability recovery increased with irradiation time up to 100 min; however, it decreased with further irradiation. This deviation could be due to particles bridge formation at later stage. In addition, optimum frequency and power of ultrasonic waves (20 kHz and 1000 W) significantly recovered the damaged permeability. Although maximum frequency (25 kHz) could not achieve maximum permeability, but higher power was quite effective. The damaged permeability recoveries of HCl and ultrasonic waves were 44.5% and 37.6% respectively, but the permeability recovery was escalated to 61.5% when HCl and ultrasonic techniques were applied together. Inorganic plugs using ultrasonic waves could chiefly be caused by cavitation, acoustic streaming, and heat generation in three different ways, such as cavitation, boundary friction and transformation upon hitting the medium.

    更新日期:2017-09-19
  • Effects of CaO and CaCO3 on Heavy Metal Capture in Bottom Ash during Municipal Solid Waste Combustion under a CO2/O2 Atmosphere
    Energy Fuels (IF 3.091) Pub Date : 2017-09-18
    Xianwen Tang, Feng Chen, Dan Shao, Ping Qin

    Experiments were conducted to investigate the influence of CaO and CaCO3 on the capture efficiency of heavy metals during the combustion of municipal solid waste (MSW) in CO2/O2 and N2/O2 atmospheres. Six heavy metal elements were studied in this paper, including Pb, Cd, Cu, Cr, Ni, and Zn. On the basis of the results, the operating temperature has a great effect on the transformation of Pb and Cd, while the amount of Cu, Cr, and Ni in the bottom ash are affected only slightly by changes in the temperature and atmosphere. The volatilization of Cd, Cu, Cr, and Zn marginally decreased with the addition of CaCO3 or in a CO2/O2 atmosphere (oxy-fuel combustion). The X-ray diffraction results show that CaO and CaCO3 have the same ability to capture heavy metals under CO2/O2 and N2/O2 atmospheres as a result of the reaction of CaO with CO2. Thermodynamic equilibrium calculations indicate that CaO or CaCO3 could barely hinder the volatilization of heavy metals by chemical reactions with the heavy metals but might hinder their volatilization by their physical adsorption. The initial forms of the heavy metals in the MSW may be another factor that affects the volatilization of the heavy metals. The importance of these forms is indicated by these six heavy metals having similar enrichment behaviors in both the CO2/O2 and N2/O2 atmospheres with CaO or CaCO3 additives; the calculations predict that these heavy metals have the same main species, except for a slight change in the content of these species.

    更新日期:2017-09-19
  • Deep Eutectic Solvents As Tuning Media Dissolving Cu+ Used in Facilitated Transport Supported Liquid Membrane for Ethylene/Ethane Separation
    Energy Fuels (IF 3.091) Pub Date : 2017-09-18
    Rong Deng, Yongli Sun, Hanrong Bi, Haozhen Dou, Huawei Yang, Baoyu Wang, Wenjun Tao, Bin Jiang

    In the petrochemical industry, it is critical to separate the light olefins/paraffins mixtures via an efficient and economic method. In this work, a series of deep eutectic solvents (DESs) (choline chloride (ChCl)-glycerol (G), ChCl-ethylene glycol (EG), 1-butyl-3-methylimidazolium chloride ([Bmim][Cl])-G, and [Bmim][Cl]-EG) dissolving CuCl were used as novel membrane liquids to fabricate supported liquid membranes (SLMs) for the C2H4/C2H6 mixture separation. Interactions based on a hydrogen bond network in different DESs were characterized by time-of-flight mass spectroscopy (TOF-MS), nuclear magnetic resonance (1H NMR), and Fourier transform infrared (FT-IR) spectroscopy. Moreover, by absorption experiments, the Cu+ activity was quantitatively described based on a first-order equilibrium model. The effects of DESs species, CuCl concentration, transmembrane pressure, temperature, and time on separation performances were investigated by C2H4/C2H6 mixture permeation experiments. CuCl/ChCl-EG-based SLMs possessed good permeability and comparable permslectivity, as well as good long-term stability, surpassing the reported polymeric membrane upper bound. Systemic study demonstrated that the strength of the hydrogen bond networks in DESs could be tailored by optimizing the combinations of the HBAs and HBDs, and eventually improved the separation performances of the CuCl/DES-based SLMs.

    更新日期:2017-09-19
  • Co-Combustion of Tannery Sludge in a Bench-Scale Fluidized-Bed Combustor: Gaseous Emissions and Cr Distribution and Speciation
    Energy Fuels (IF 3.091) Pub Date : 2017-09-18
    Hao Dong, Xuguang Jiang, Guojun Lv, Fei Wang, Qunxing Huang, Yong Chi, Jianhua Yan, Weizhong Yuan, Xijiong Chen, Weizhong Luo

    In this study, 11 coal mono-combustion tests and four co-combustion tests of coal and tannery sludge were conducted on a 35 kW fluidized-bed combustor. The combustion behavior and emission characteristics of the fuels were investigated on a bubbling fluidized bed (BFB) and a circulating fluidized bed (CFB). The effects of an excess air ratio, primary air rate, secondary air ratio, and fuel type on flue gas emissions were studied. The results showed that the fluidization status and temperature distribution had direct influences on CO emission. Sufficient fluidization and high temperature effectively reduced CO emission. NOx emission was relatively sensitive to the excess air ratio and increased with increasing excess air ratio. By comparing BFB and CFB, we found that CFBs have an advantage in optimizing combustion and controlling emissions by enhancing mixing and increasing freeboard temperatures. The Cr speciation and distribution among different ash types were extensively investigated in four co-combustion tests. The results showed that the distribution modes of Cr in BFBs and CFBs were different and determined by separate fluid dynamics modes of sludge ash particles in the combustor. The extent of Cr oxidation in ash in CFB tests was higher than that in BFB tests, particularly for bottom ash and heat exchanger ash, due to longer residence times in high-temperature regions.

    更新日期:2017-09-19
  • A Simplified Model Accounting for the Combustion of Pulverized Coal Char Particles in a Drop Tube Furnace
    Energy Fuels (IF 3.091) Pub Date : 2017-09-18
    Patrick Gilot, Alain Brillard, Jean-François Brilhac, Cornelius Schönnenbeck

    A simple model is proposed, which predicts the evolutions versus time of the temperature and of the carbonaceous material conversion of a coal char particle during its combustion in a drop tube furnace under a very high heating rate of 1500 K/s. The values of the intrinsic reactivity parameters are obtained performing thermogravimetric analyses of the coal char particles in a thermobalance under a low heating rate of 10 K/min. In this simple model, the local evolutions of the particle porosity and density are not accounted for as only their mean values are considered at any time of the combustion process. The oxygen concentration gradient within the particle is accounted for, once a particle effectiveness factor related to the Thiele modulus is estimated. Comparisons between the experimental and simulated temperatures of the particle are performed for three regulation temperatures of the drop tube furnace, and the combustion regimes are analyzed in terms of the effectiveness factor of the particle.

    更新日期:2017-09-18
  • Influences of CO2 injection into deep coal seams: A review
    Energy Fuels (IF 3.091) Pub Date : 2017-09-18
    Mandadige Samintha Anne Perera

    For nearly 20 years, CO2 has been injected into coal seams to enhance the recovery of methane in a process known as enhanced coal bed methane (ECBM). However, there is a huge complexity associated with this process mainly due to the generating complex coal chemico-physical structure re-arrangement. This review paper aims to comprehensively discuss two main influencing factors upon CO2 injection in deep coal seams: 1) mobilization of hydrocarbon and, 2) coal matrix swelling. CO2 injection into deep coal seams may remove available polycyclic aromatic hydrocarbons (PAHs) from the coal matrix and mobilize them in the coal seam. The amount of hydrocarbon that is mobilized from the coal matrix by the injected CO2 is dependent on coal rank, maceral content, type of available some hydrocarbons in the coal mass (both dissolving and non-dissolving types) and phase state of the injected CO2 in the seam. Supercritical CO2 has greater solvent ability and therefore has ability to extract a greater percentage of hydrocarbon from the coal matrix. This mobilization of the organic constituents of the coal matrix by the injected CO2 causes many environmental issues. For examples, PAHs exist in high-volatile bituminous coal are harmful to biota and environment, even at relatively low concentrations. On the other hand, adsorption of the injected CO2 into the coal mass causes it to be swelled leading significant alternations in its internal coal mass structure, resulting in great modifications in its flow and strength properties. This CO2 adsorption induced coal matrix swelling process is reduced with increasing temperature, exhibits inverted-U shaped variation with coal rank and largely dependent on the pressure and the physical state of the injected CO2, where supercritical CO2 creates much greater swelling effect compared to gas/ liquid CO2 due to its higher chemical potential. Potential coal seams for CO2 sequestration process are available at extremely deep locations and there is a high possibility of phase change from gas/liquid to supercritical state and thus the likely have high swelling rates.

    更新日期:2017-09-18
  • Impact of Different Experimental Heating Rates on Calculated Hydrocarbon Generation Kinetics
    Energy Fuels (IF 3.091) Pub Date : 2017-09-15
    Yuanyuan Ma, Tingting Cao, Lloyd Snowdon, Menhui Qian, Qigui Jiang, Maowen Li, Nicolaj Mahlstedt, Brian Horsfield

    Four organic-rich samples from four basins in China have been analyzed, using open-system bulk pyrolysis with heating rates ranging from 0.7 K/min to 40 K/min. The resulting programs have been digitized and first-order Arrhenius kinetics have been optimized using groups of different heating rate ranges. Low heating rate optimization was performed for data generated at 5 K/min, 2 K/min, and either 0.7 or 1 K/min. High heating rate optimization used experimental rates of 15, 25, and 40 K/min. Optimization was also completed for wide heating rate ranges at 40 K/min, 15 K/min, and either 1 or 2 K/min. The kinetics solutions were then used to calculate bulk hydrocarbon generation at a geological heating rate of 3 K/Ma, in order to determine the impact of using different experimental approaches. The results showed that low versus high and narrow versus wide heating rates did not yield systematically different results. The highest predicted geological temperature was observed for the low heating rates (Huadian, Ordos), high heating rates (Maoming), and wide heating rate range (Wang18 and Ordos). The wide heating rate ranges yielded predicted temperatures that were between the high and low heating rates for Huadian and Maoming but higher than or equal to both narrow range rates for Wang18 and Ordos. The results from the Source Rock Analyzer optimized using Kinetics2015 software predicted similar activation energy distributions and frequency factors and, consequently, similar geological temperatures for all samples to the Rock-Eval results optimized using Kinetics2005 software, although the samples run on the two instruments were not homogeneous aliquots but rather separate pieces broken from field or core samples. Predicted temperatures for 50% transformation at a geological heating rate show a variability of less than ±6 °C, which translates to a burial difference of <300 m for a basin with a “normal” geothermal gradient.

    更新日期:2017-09-15
  • Energy Recovery from Rice Straw through Hydrothermal Pretreatment and Subsequent Biomethane Production
    Energy Fuels (IF 3.091) Pub Date : 2017-09-15
    Leilei He, He Huang, Zhenya Zhang, Zhongfang Lei, Bin-Le Lin

    Rice straw is an abundant agricultural waste in Asia. Anaerobic digestion (AD) as an environmentally friendly process for bioenergy recovery is expected to solve the environmental issues brought about by open burning of rice straw. In order to test the feasibility and scalability of hydrothermal treatment (HTT) on rice straw for subsequent methane production from pretreated straw, this study attempted two peak HTT temperatures (150 and 210 °C, i.e. HTT150 and HTT210, respectively) for holding 0–30 min to pretreat rice straw which was then used for mesophilic methane fermentation. Thereafter energy balance and energy recovery were analyzed on HTT and subsequent AD of rice straw. Results show that HTT150 exhibited a positive effect on subsequent methane production, achieving the highest methane yield of 134 mL (STP) for per gram of added volatile solid (VSadded) of rice straw after being hydrothermally pretreated at 150 °C for 20 min. The maximum specific methane production rate (μ), around 17–40% higher than the control (without pretreatment), was achieved from HTT150 pretreated rice straw. HTT210 was found to have a negative effect on subsequent AD. Considering disposal of rice straw by HTT coupling with subsequent methane production, the highest net energy gain (ΔE = Eout – Ein), energy ratio (Eout/Ein), and energy recovery (in comparison to direct combustion) were obtained at HTT150 for 20 min, about 2741 MJ/t, 2.7, and 30.7%, respectively. Results from this work imply that HTT temperature is critically important when subsequent AD for enhanced methane production and energy balance of the whole disposal system are targeted.

    更新日期:2017-09-15
  • Reversibility of asphaltene aggregation as revealed by Magnetic Resonance Imaging in situ
    Energy Fuels (IF 3.091) Pub Date : 2017-09-14
    Evgeny V. Morozov, Oleg Nikolaevich Martyanov

    Aggregation of asphaltenes followed by precipitation presents severe problem for existing technologies of the production, recovery, and processing of heavy oils. Better understanding of asphaltenes behavior behind the processes of their precipitation/dissolution is vital to address this issue. While investigating inhomogeneity of different oil systems, the reversibility of asphaltene aggregation process initiated by flocculant in either asphaltene solution in toluene or crude heavy oil was revealed and investigated using Magnetic Resonance Imaging (MRI) method. It was found out that the inhomogeneous distribution of the flocculant initiates local spatial-selective asphaltenes aggregation registered in a thin layer around the flocculant/oil sample interface. The local excess of flocculant concentration over the threshold of asphaltene precipitation onset is a driving force of this process. As the flocculant diffuses into the volume of the sample a decrease of the asphaltene flocculated area is observed until it disappears when the equilibrium composition throughout the whole volume of the system is achieved. Depending on the overall flocculant concentration, the asphaltene aggregation may not be reversible and could be followed by subsequent precipitation of the asphaltene aggregates. The similarity of the phenomena observed for the model asphaltene solutions and crude heavy oil samples was established. Partial mechanical stirring of the multicomponent system comprising flocculant and oil or asphaltene solution does not prevent the formation of the local zones with increased concentration of asphaltene aggregates those sizes evolve depending on the flocculant concentration. The results obtained in this work are consistent well with the generally accepted concept of asphaltene precipitation reversibility depending on the system composition, and compatible with the observations obtained by other methods. The approach presented can provide deeper insight into the asphaltene precipitation reversibility issue and facilitate the understanding of asphaltene behavior in heavy oils.

    更新日期:2017-09-15
  • Imaging of Flames in Cement Kilns to Study the Influence of Different Fuel Types
    Energy Fuels (IF 3.091) Pub Date : 2017-09-14
    Morten Nedergaard Pedersen, Mads NIelsen, Sønnik Clausen, Peter Arendt Jensen, Lars Skaarup Jensen, Kim Dam-Johansen

    The cement industry aims to use an increased amount of alternative fuels to reduce production costs and CO2 emissions. In this study three cement plants firing different kinds and percentages of alternative fuel were studied. A specially developed camera setup was used to monitor the flames in the three cement kilns and assess the effect of alternative fuels on the flame. It was found that co-firing with solid recovered fuel (SRF) would delay the ignition point by about 2 meters and lower the intensity and temperature of the kiln flame compared to a fossil fuel flame. This is related to a larger particle size and moisture content of the alternative fuels, which lowers the conversion rate compared to fossil fuels. The consequences can be a lower kiln temperature and cement quality. The longer conversion time may also lead to the possibility of localized reducing conditions in the cement kiln, which can have a negative impact on the clinker quality and process stability. The burner design may alleviate some of the issues encountered with SRF co-firing. At one of the test plants the burner was changed from a design with an annular channel for axial air to a jet design. This proved to be beneficial for an early ignition and improved dispersion of the fuel and led to an increase in cement quality and higher use of SRF.

    更新日期:2017-09-15
  • Production of Liquefied Oil Palm Empty Fruit Bunch (EFB) based Polyols via Microwave Heating
    Energy Fuels (IF 3.091) Pub Date : 2017-09-14
    Umar Adli Amran, Sarani Zakaria, Chin Hua Chia, Zhen Fang, Mohamad Zulfahdli Masli

    Optimization of microwave-assisted liquefaction of oil palm empty fruit bunch fiber (EFB) and EFB cellulose (EFBC) in ethylene glycol (EG) were carried out to produce polyols. The liquefaction residues and hydroxyl numbers of resultant polyols from respective sources were studied and compared. EFB produced minimum residue of 3.22% at the optimal parameters of 160°C and 15 min. Meanwhile optimum liquefaction of EFBC produced 1.03% residue at 175°C and 40 min. The maximum hydroxyl numbers of both EFB (749.22 mgKOH/g) and EFBC (639.91 mgKOH/g) polyols were obtained at optimum conditions. FTIR analysis revealed the degradation mechanism of cellulose and lignin in EFB at different temperatures. Lignin was found to be liquefied easily at lower temperatures (130 and 145°C). However most of the cellulose began to be liquefied at the optimum temperature (160°C) and severely degraded at higher temperatures (175 and 190°C).

    更新日期:2017-09-15
  • Experimental Investigation of the Transformation of Oil Shale with Fracturing Fluids under Microwave Heating in the Presence of Nanoparticles
    Energy Fuels (IF 3.091) Pub Date : 2017-09-15
    Zhaozhong Yang, Jingyi Zhu, Xiaogang Li, Dan Luo, Shuangyu Qi, Min Jia

    Traditional methods of exploiting oil shale such as mining or in situ electric heating cause environmental pollution, and they have huge energy losses and high costs. These problems can be solved by combining microwave heating with hydraulic fracturing for the in situ exploitation of oil shale. In this study, an experimental microwave apparatus was manufactured for laboratory experiments. Different weight proportions of iron oxide nanoparticles (0.1, 0.5, and 1 wt %), microwave output power (600, 800, and 1000 W), and ultimate reaction temperatures (550, 750, and 950 °C) were taken into account in the design of an orthogonal experiment. Temperature distributions were influenced by microwave power, as well as by the concentration of iron oxide nanoparticles. The iron oxide nanoparticles facilitated a noticeable rise in the temperature of the oil shale in a short time. The experimental results confirmed the advantages of microwave heating, compared to conventional heating, in terms of temperature increases and improved yields of higher quality oil. Specifically, the oil collected under microwave irradiation contained more saturation and aromatics, and less sulfur and nitrogen, than that obtained by conventional heating. The highest oil yield and the best oil quality were obtained with the parameters of output power of 800 W, ultimate reaction temperature of 950 °C, and iron oxide nanoparticles at 0.1 wt %. Our findings contribute to the application of microwave technology to unconventional resources, and field tests at small scale should be supported.

    更新日期:2017-09-15
  • Paleoenvironment and Its Control of the Formation of Oligocene Marine Source Rocks in the Deep-Water Area of the Northern South China Sea
    Energy Fuels (IF 3.091) Pub Date : 2017-09-15
    Wenhao Li, Zhihuan Zhang

    This article discusses the paleoenvironment and its control on Oligocene source rock formation in the deep water area of the northern South China Sea (SCS), including the deep water area of the Qiongdongnan (QDN) Basin and Baiyun Sag of the Pearl River Mouth (PRM) Basin. During E3y and E3l deposition, the terrigenous detrital matter (TDM) inputs were moderate to high and moderate, respectively, as indicated by TiO2 values and SiO2/Al2O3 ratios, which accordingly diluted primary production, causing low to moderate and moderate productivity, respectively. The bottom water was oxic because of abundant TDM input, which was unbeneficial for organic matter accumulation. In this environment, algal organic matter could not be preserved. Terrigenous organic matter (TOM) is the main controlling factor of Oligocene source rock formation in the deep-water area of the QDN basin. Source rocks with high organic matter content in the Yacheng Formation could not be formed, although there was moderate to high TOM input in this period, as suggested by relatively high oleanane/αβ C30hopane (OL/C30H) ratios and low ααα20RC27/ααα20RC29 sterane (C27/C29) ratios. During E3l deposition, the influx of TOM was reduced, making conditions unsuitable for high organic carbon source rock formation. In contrast to the QDN basin, there was an influx of fresh water (the ancient Pearl River) into the PRM basin, which significantly influenced the source rock formation in the Baiyun Sag. Thus, TOM and TDM inputs were abundant during E3z deposition. Increased content of TDM not only reduced primary production, causing moderate and low productivity during E3e and E3z deposition, respectively, but also contributed to oxic conditions. Although most algal organic matter could not be preserved in the oxygenated water column, part of the algal organic matter could have accumulated due to the high sedimentary rate suggested by high content of TDM, which supported Oligocene source rock formation in the Baiyun Sag. TOM mainly controlled the development of source rocks in the Enping Formation, and source rocks with relatively high organic matter abundance could be formed. However, multiple factors (besides the main factors TOM and TDM, paleoproductivity and redox conditions were also included) influenced the source rocks in the Zhuhai Formation. Organic carbon-rich source rocks could have developed in this period.

    更新日期:2017-09-15
  • Comparison of the Reburning Chemistry in O2/N2, O2/CO2, and O2/H2O Atmospheres
    Energy Fuels (IF 3.091) Pub Date : 2017-09-15
    Yizhuo He, Jianghui Luo, Yangguang Li, Huiqiao Jia, Feng Wang, Chun Zou, Chuguang Zheng

    The reburning chemistry in oxy-fuel and oxy-steam combustion of methane was investigated both experimentally and numerically. Comparison experiments in O2/N2, O2/CO2, and O2/H2O atmospheres were performed in a flow reactor at atmospheric pressure with equivalence ratio ranging from fuel-rich to fuel-lean and temperature from 973 to 1773 K. Experimental results showed that compared with N2 and CO2 atmospheres NO reduction observed in H2O atmosphere is the lowest under fuel-rich and stoichiometric conditions, while it is the highest under fuel-lean conditions. The NO reduction intensity in CO2 atmosphere lies between N2 and H2O atmosphere under fuel-rich and fuel-lean conditions; however, it is the highest under stoichiometric conditions. A chemical kinetic mechanism, which was hierarchically structured and updated in our previous work, captured the main characteristics and quantity of CO and NO formation satisfactorily even under fuel-lean conditions. According to the analysis from a chemical kinetic point of view, CO2 and H2O exert significant impacts on altering the radical pool structure to OH dominant, subsequently varying the availability of hydrocarbon radical as a reducing agent, which is the primary reason for the different degrees of NO reduction under fuel-rich, stoichiometric, and fuel-lean conditions. In addition, CO2 and H2O also impact the NO reduction by nitrogen-containing radicals. For CO2 atmosphere, NCO radical always occupies an overwhelmingly dominant position in NO reduction due to HCN → CH3CN → CH2CN → CN → NCO, and HNCO → NCO channel is amplified substantially. For H2O atmosphere, under fuel-rich and stoichiometric conditions, NH2 and NH radical are dominant due to the enhancement of NCO → HNCO → NH2 → NH channel. Under fuel-lean conditions, NCO radical is dominant due to the strength of HNCO → NCO channel.

    更新日期:2017-09-15
  • X-ray Photoelectron Spectroscopy Analysis of Hydrotreated Athabasca Asphaltenes
    Energy Fuels (IF 3.091) Pub Date : 2017-09-15
    Héctor J. Guzmán, Fernanda Isquierdo, Lante Carbognani, Gerardo Vitale, Carlos E. Scott, Pedro Pereira-Almao

    C7 asphaltenes from Athabasca crude oil were hydrotreated using a commercial NiW/Al2O3 catalyst and analyzed using X-ray photoelectron spectroscopy. Results showed that the catalyst performed better in the removal of sulfur rather than nitrogen and that sulfur concentration is higher at the surface in comparison to the bulk structure. Moreover, the sample after reaction had a higher oxygen content in comparison to the untreated asphaltene, indicating poor hydrodeoxygenation performance of the catalyst in addition to a higher reactivity toward atmospheric oxygen at the surface of the asphaltene. The latter is proposed to arise once the layer of resin covering the asphaltene is partially converted during the hydrotreating process.

    更新日期:2017-09-15
  • A Bayesian Estimation Model for Transient Engine Exhaust Characterization Using Fourier Transform Infrared Spectroscopy
    Energy Fuels (IF 3.091) Pub Date : 2017-09-15
    David Wilson, Casey Allen

    Comprehensive emissions models extensively use engine exhaust data from vehicle experiments to represent the relationship between fuel composition and pollutants. However, the predicted emissions from these models often neglect the effects of transients and speed-load history. Fourier transform infrared (FTIR) spectroscopy is a high frequency measurement technique capable of comprehensive speciation. However, due to long residence times of exhaust within a FTIR spectrometer gas cell, FTIR measurements are contaminated by the effects of historical emissions, precluding the attainment of time-resolved engine exhaust data. This work presents a Bayesian estimation model for processing FTIR measurements to obtain accurate estimations of instantaneous engine exhaust composition. The Bayesian model utilizes a simple model of the mixing dynamics of the gas cell and measurement noise statistics to estimate the composition of exhaust entering the FTIR gas cell during a measurement period. To validate the estimation model, synthetic FTIR measurements are generated from simulated engine exhaust data from the Federal Test Procedure driving cycle. These synthetic measurements are processed by the estimation model, which is shown to yield improved estimations of instantaneous composition as compared to the raw FTIR measurements, although the degree of improvement depends on the magnitude of measurement noise and flow rate through the FTIR gas cell. For a measurement noise standard deviation of 0.5% of the maximum measurement, the estimation model improved estimates of instantaneous NO emission by approximately 42.5% on average, while about a 7.5% improvement was achieved for a measurement noise standard deviation of 2% of the maximum measurement for a FTIR flow rate of 10 L/min. For a flow rate of 25 L/min, improvements of approximately 41.5% and 6% were achieved for measurement noise standard deviations of 0.5% and 2% of the maximum measurements, respectively. The application of the model in this work is to generate time-resolved emissions estimates to further elucidate the relationship between fuel composition and engine emissions.

    更新日期:2017-09-15
  • Fractal Analysis of Pore Network in Tight Gas Sandstones Using NMR Method: A Case Study from the Ordos Basin, China
    Energy Fuels (IF 3.091) Pub Date : 2017-09-14
    Xinhe Shao, Xiongqi Pang, Hui Li, Xue Zhang

    To characterize the pore structure and quantify fractal dimensions of tight gas sandstones, a case study is performed on the Lower-Middle Permian tight sandstones in the Ordos Basin in China by conducting a series of experiments including X-ray diffraction (XRD) analysis, routine petrophysical measurements, thin section and scanning electronic microscope (SEM) observations, and nuclear magnetic resonance (NMR) experiment. The studied tight sandstones mainly consist of quartz and clay minerals, and pore types include primary intergranular pores, inter- and intragranular dissolution pores, as well as micropores associated with clay aggregates; T2 spectra reflect three types of pore size distributions in the studied samples, indicating a rather irregular pore distribution pattern in tight sandstones; NMR can estimate porosity of tight sandstones accurately, and movable-fluid porosity from NMR can better reflect the permeability of tight sandstones than total porosity. Two fractal dimensions, Dbnd (with respect to bound-fluid pores) and Dmov (with respect to movable-fluid pores), are calculated to be 1.1135–1.8116 (average 1.4750) and 2.6816–2.9932 (average 2.8921), respectively. Dbnd increases with the decrease of detrital quartz content and the increase of clay mineral content, whereas Dmov increases with the increase in authigenic quartz content and the decrease of detrital quartz content; fractal dimensions can reflect the physical properties of tight sandstones, as large Dbnd and Dmov values typically result in low movable-fluid porosity and permeability; the pore network of tight sandstones can be considered as a dual-scale pore system based on fractal theory, whereas Dbnd and Dmov can reveal the roughness of bound-fluid pore surface and the distribution of movable-fluid pores, respectively. This study shows that NMR fractal dimension can be employed as an effective indicator to characterize the pore network of tight sandstones.

    更新日期:2017-09-15
  • Zeolite-Supported Iron Oxides as Durable and Selective Oxygen Carriers for Chemical Looping Combustion
    Energy Fuels (IF 3.091) Pub Date : 2017-09-14
    Lu Liu, Yiqing Wu, Junkai Hu, Dongxia Liu, Michael R. Zachariah

    Chemical looping combustion (CLC) is a promising technology for fossil fuel combustion with inherent CO2 separation from flue gases, circumventing high cost for CO2 capture and NOx elimination as in conventional combustion processes. Metal oxides are commonly used as oxygen carriers (OCs) in CLC. However, sintering and coking of OCs and the consequent degradation in their activity and durability during multiple cycles inhibit the practical applications of CLC technology. In the present study, we employed a silicalite-1 zeolite support to achieve OCs with high resistance against sintering and coking in CLC. Iron oxides (Fe2O3) with methane fuel were employed to demonstrate the approach and to quantify the influence of silicalite-1 support on conversion efficiency, durability, and selectivity of these OCs in CLC cycles. Two iron oxide–zeolite geometrical structures, a core–shell Fe2O3@silicalite-1 and a Fe2O3-impregnated silicalite-1 (Fe2O3/silicalite-1), were created to improve Fe2O3 stability. The CLC tests showed that both structures led to less aggregation of Fe2O3 OCs at 1223 K. A comparison between Fe2O3/silicalite-1 and Fe2O3@silicalite-1 in CLC tests illustrates that Fe2O3 impregnated in zeolite had higher durability than in the core–shell structure. The selectivity of CH4 to CO2 followed the order of Fe2O3/silicalite-1 > Fe2O3@silicalite-1 ≫ bare Fe2O3. The high selectivity of Fe2O3/silicalite-1 to CO2 in CLC tests can be attributed to the encapsulation of Fe2O3 inside channels of silicalite-1 that provides physical barriers for aggregation of OCs in CLC cycles as well as coke deposition on OCs. In conclusion, our study of the structure–function relation for silicalite-1-supported Fe2O3 OCs can form the basis for the development of silicalite-1 as an efficient support in chemical looping applications.

    更新日期:2017-09-15
  • Membrane Evaporation for Energy Saving in CO2 Chemical Absorption Process Using a Polybenzimidazole Film: Mass and Heat Transfer
    Energy Fuels (IF 3.091) Pub Date : 2017-09-14
    Qinhui Ma, Mengxiang Fang, Tao Wang, Hai Yu, Paul H. M. Feron

    Intensive energy consumption remains a major challenge for the commercial application of CO2 chemical absorption. In this study, a membrane evaporation system based on PBI film was proposed for recovering latent heat from the hot lean CO2 solution in order to reduce the energy penalty during CO2 capture process. The effects of key operational parameters (i.e., evaporation temperature, sweeping gas flow rate, and liquid flow rate) were systematically investigated. It was found that both vapor flux and recovered heat flux had exponential increases when the evaporation temperature increased. Sweeping gas flow rate and liquid flow rate had limited effects on both mass and heat transfer in the membrane evaporation process. The PBI film showed good stability during a 14 days’ duration experiment. Reducing the membrane thickness can significantly improve the membrane evaporation performance. From the viewpoint of energy evaluation, when the evaporation mass reached 10 g/kg solution, the regeneration energy consumption could be reduced by 0.47 MJ/kg CO2, which demonstrates a great potential to save energy consumption in large-scale CO2 chemical absorption processes.

    更新日期:2017-09-15
  • Petroleomic Characterization of Pyrolysis Bio-oils: A Review
    Energy Fuels (IF 3.091) Pub Date : 2017-09-14
    Martin Staš, Josef Chudoba, David Kubicka, Jozef Blazek, Milan Pospíšil

    Pyrolysis bio-oils could be used in the future as biofuels or as a source of valuable oxygen-containing chemicals. To facilitate efficient exploitation of bio-oils, a detailed understanding of their structure is necessary. Over the last decade, petroleomic analysis has been widely applied to characterize pyrolysis bio-oils from the lignocellulosic biomass. Typically, a petroleomic analysis has been performed using high-resolution mass spectrometry (HRMS). HRMS has enabled the researchers to determine the molecular weights and molecular formulas of thousands of less volatile and nonvolatile, high-molecular-weight bio-oil compounds to obtain structural information that cannot be obtained using any other method. Here, we discuss the theoretical principles of HRMS and present an overview of the investigations regarding the petroleomic characterization of pyrolysis bio-oils and their key findings. In addition, this review outlines the current knowledge of the structure of bio-oil compounds detectable by HRMS. This could help to understand the chemical composition of bio-oils in more detail and facilitate the design of processes for bio-oil upgrading and further utilization.

    更新日期:2017-09-15
  • TG-DSC study to measure heat of desorption of water during the thermal drying of coal and to examine role of adsorption of water vapor for examining spontaneous heating of coal over 100 °C
    Energy Fuels (IF 3.091) Pub Date : 2017-09-14
    Trairat Muangthong-on, Janewit Wannapeera, Hideaki Ohgaki, Kouichi Miura

    A sensitive thermogravimetric analysis and differential scanning calorimetry (TG-DSC) apparatus enabled accurate measurement of the heat of adsorption/desorption of water on/from coal at temperatures over 100 °C. This technique was first used to measure the heat of desorption of water during the thermal drying of as-received coal. For three low-rank coals, the heats of desorption were almost constant at 2300−2350 kJ/kg until the water content decreased to 0.35 kg/kg-dried coal, which is close to the heat of vaporization, and gradually increased to reach ~5000 kJ/kg at the completion of drying at 107 °C. The role of adsorption of water vapor on the dried coal in relation to the coal-oxygen interaction was then examined to evaluate the propensity to spontaneous heating of dried coal. For the three coals tested, the heat generated by the adsorption of water vapor from moist air with a relative humidity of 0.15 was 90−130 kJ/kg-dried coal in 30 min; these values are 1.2−4 times larger than the heats generated by the coal-oxygen interaction, even at 107 °C. This observation suggests that the adsorption of water vapor plays an important role in the spontaneous heating of coal, even over 100 °C. The transient changes in the heats of adsorption/desorption of water on the approach to equilibrium were also successfully estimated and discussed in relation to the isosteric heat of adsorption/desorption and heat of vaporization of water.

    更新日期:2017-09-15
  • Toward Efficient CO2 Capture Solvent Design by Analyzing the Effect of Chain Lengths and Amino Types to the Absorption Capacity, Bicarbonate/Carbamate and Cyclic Capacity
    Energy Fuels (IF 3.091) Pub Date : 2017-09-14
    Rui Zhang, Qi Yang, ZhiWu Liang, Graeme Puxty, Roger J. Mulder, Joanna E. Cosgriff, Hai Yu, Xin Yang, Ying Xue

    Chemical absorption using aqueous amine-based solutions is the leading method for large-scale CO2 capture in industrial plants. This technology, however, still faces many challenges, in particular the high energy requirements for solvent regeneration, which limit the economic viability of the technology. To guide the development of more energy efficient amine solvents, this work studied the effect of molecular characteristics of diamines, including carbon chain length and type of amino functional group, on CO2 absorption and desorption performance. Six linear terminal diamines (NH2CH2CH2-R, R = NH2, NHCH3, N(CH3)2, CH2NH2, CH2NHCH3 and CH2N(NH3)2) were investigated and two monoamines, monoethanolamine (NH2CH2CH2OH, MEA) and 3-aminopropanol (NH2CH2CH2CH2OH, 3AP), were also tested as benchmarks. The CO2 absorption capacity in each amine was measured at 40 °C under atmospheric pressure using different CO2 gas partial pressures. 13C and 1H NMR spectroscopy were used to identify and quantify species present in the CO2-amine-H2O system. Computational modelling was also carried out using Gaussian software to explain the effect of chain length change on the stability of the monocarbamate. The experimental results showed that the chain length extension from C2 to C3 led to a higher CO2 absorption capacity and more bicarbonate formation during the CO2 absorption process, and the computational study results supported this conclusion. In addition, the experimental results also demonstrated that increasing the substitution on one N atom in the tested diamines is favorable for a higher CO2 absorption capacity and more bicarbonate formation under a CO2 partial pressure of 101 kPa. Both chain length extension from C2 to C3 and an increase in the number of substituents on one N atom yield better performance in the CO2 desorption with regards to the CO2 higher cyclic capacity and faster initial CO2 release rate for the tested amines.

    更新日期:2017-09-15
  • A comparison of NaOH, Fenton and their combined pretreatments for improving saccharification of corn stalks
    Energy Fuels (IF 3.091) Pub Date : 2017-09-14
    Menghui Yu, Sandra Chang, Dongsheng Li, Chengming Zhang, Li Jiang, Yaxin Han, Lisong Qi, Jihong Li, Shizhong Li

    In this study, the effectiveness of NaOH extraction (AE), Fenton oxidation (FO) and synergistic pretreatment using AE and FO for enzymatic saccharification of corn stalks (CS) was compared by statistical analyses. The results showed that AE-FO treatment resulted in statistically higher enzymolysis efficiency than single AE and single FO treatments. Compared with single AE and FO treatments, AE-FO resulted in statistically significant higher lignin removal and xylan removal, consequently improving the cellulose accessibility to cellulase. Among various synergistic pretreatment parameters, utilizing Plackett-Burman design determined the most effective factor improving cellulose accessibility to cellulase was NaOH loading. The results that we obtained could be extended to help further improve the synergistic pretreatment process for using CS for the production of biofuels and sugar-based chemicals.

    更新日期:2017-09-15
  • Research on the Synthesis of Ionic Liquids/Layered Double Hydroxides Intercalation Composites and Their Application on the Removal of Naphthenic Acid from Oil
    Energy Fuels (IF 3.091) Pub Date : 2017-09-14
    XiangSheng Shao, Guanhao Liu, Jingyi Yang, Xinru Xu

    Three kinds of imidazolium ionic liquids were synthesized, and [Bmim][CH3COO] was selected as a result of its higher deacidification rate at a lower cost. Then, the synthetic ionic liquid was immobilized by layered double hydroxides, and the composites were characterized by Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (1H NMR), carbon-13 nuclear magnetic resonance (13C NMR), electrospray ionization mass spectrometry (ESI–MS), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and N2 adsorption–desorption isotherms. The results showed that [Bmim][CH3COO] synthesized by the intercalation method exhibited a better deacidification property compared to the dipping method. When [Bmim][CH3COO]/Mg0.5Ca2.5Al1 (I) synthesized by the intercalation method was used as a reagent, the deacidification rate reached 97.61%. The optimum reaction conditions were at the reagent/oil mass ratio of 0.08, the reaction temperature of 313 K, and the reaction time of 1 h. Moreover, the composites still had excellent performance on deacidification after being repeatedly used 6 times.

    更新日期:2017-09-14
  • Off-Gassing of VOCs and Permanent Gases during Storage of Torrefied and Steam Exploded Wood
    Energy Fuels (IF 3.091) Pub Date : 2017-09-14
    Eleonora Borén, Fahimeh Yazdanpanah, Roger Lindahl, Christoph Schilling, Richard P. Chandra, Bahman Ghiasi, Yong Tang, Shahabaddine Sokhansanj, Markus Broström, Sylvia H. Larsson

    Thermal treatment for upgrading of low-value feedstocks to improve fuel properties has gained large industrial interest in recent years. From a storage and transport perspective, hazardous off-gassing could be expected to decrease through the degradation of reactive biomass components. However, thermal treatment could also shift chemical compositions of volatile organic components, VOCs. While technologies are approaching commercialization, off-gassing behavior of the products, especially in terms of VOCs, is still unknown. In the present study, we measured off-gassing of VOCs together with CO, CO2, CH4, and O2 depletion from torrefied and steam exploded softwood during closed storage. The storage temperature, head space gas (air and N2), and storage time were varied. VOCs were monitored with a newly developed protocol based on active sampling with Tenax TA absorbent analyzed by thermal desorption-GC/MS. High VOC levels were found for both untreated and steam exploded softwood, but with a complete shift in composition from terpenes dominating the storage gas for untreated wood samples to an abundance of furfural in the headspace of steam exploded wood. Torrefied material emitted low levels of VOCs. By using multivariate statistics, it was shown that for both treatment methods and within the ranges tested, VOC off-gassing was affected first by the storage temperature and second by increasing treatment severity. Both steam exploded and torrefied biomass formed lower levels of CO than the reference biomass, but steam explosion caused a more severe O2 depletion.

    更新日期:2017-09-14
  • A Magnetic Resonance Study of Low Salinity Waterflooding for Enhanced Oil Recovery
    Energy Fuels (IF 3.091) Pub Date : 2017-09-14
    Ming Li, Sarah Vashaee, Laura Romero-Zerón, Florin Marica, Bruce J. Balcom

    Low salinity waterflooding (LSF) has been proposed to improve oil recovery, with major projects in progress worldwide. There is however no consensus on the mechanisms of LSF for enhanced oil recovery (EOR). Wettability change is the most widely accepted mechanism. In this work, magnetic resonance (MR) and magnetic resonance imaging (MRI) were employed to monitor oil displacement processes during model laboratory scale LSF experiments. The MR and MRI measurements permit evaluation of putative LSF mechanisms. Two clay-coated sand packs, one with nonswelling kaolinite, the other with swelling montmorillonite, were prepared as model porous media for LSF. The interactions between pore fluids (oil and water) and the clay-coated pore surfaces were evaluated with relaxation time measurements. A MRI methodology, spin echo single point imaging (SE-SPI), was employed to spatially resolve the T2 distribution along the sand pack. The oil saturation profiles were determined from SE-SPI measurements. A new differential relaxation time distribution method is proposed in this work for oil saturation estimation. The pore fluid self-diffusion coefficients were measured. The mechanism of wettability change for LSF is suggested on the basis of the oil diffusion coefficient variation with LSF. The similarities and differences between the kaolinite and montmorillonite behaviors are discussed. This work demonstrates that MR and MRI are robust tools to monitor oil displacement processes, with the potential to reveal the mechanisms of LSF and other procedures for enhanced oil recovery.

    更新日期:2017-09-14
  • Experimental and Kinetic Modeling Study on Self-Ignition of α-Methylnaphthalene in a Heated Rapid Compression Machine
    Energy Fuels (IF 3.091) Pub Date : 2017-09-13
    Shuzhou Sun, Liang Yu, Sixu Wang, Yebing Mao, Xingcai Lu

    As an important component of diesel and kerosene surrogates, the experimental study and chemical kinetic modeling of α-methylnaphthalene (AMN) are still very insufficient. The ignition delay of an AMN/O2/Ar mixture in a heated rapid compression machine (RCM) was measured in this study. The data were obtained for equivalence ratios of 0.7, 1, and 1.2, at pressures of 12, 15, and 20 bar, over the temperature range of 860–1040 K. A semi-detailed kinetic mechanism for the oxidation of AMN was established, which consists of 196 species and 1330 reactions. In comparison to the different previous mechanism, the new mechanism can more accurately predict the ignition delay of AMN in RCM and shock tube experiments. It can also accurately predict the experimental data obtained in a jet-stirred reactor from the literature. The ignition delays using adiabatic constant-volume simulation and RCM simulation were compared, which indicated that RCM simulation could better predict the experimental data. Sensitivity and reaction path analysis were also carried out to explore the effect of key reactions and paths on AMN ignition.

    更新日期:2017-09-14
  • Impact of Fuel Composition and Intake Pressure on Lean Autoignition of Surrogate Gasoline Fuels in a CFR Engine
    Energy Fuels (IF 3.091) Pub Date : 2017-09-13
    Vickey Kalaskar, Dongil Kang, André L. Boehman

    The critical compression ratio (CCR) criterion (defined as the minimum compression ratio at which the fuel shows initial signs of autoignition) was examined for various gasoline surrogate fuels in a motored engine. This investigation builds on the concept of CCR which is a good indicator of a fuel’s autoignition characteristics, to study the fuel compositional effects with increasing intake manifold pressure. The blends consisted of binary and ternary mixtures of n-heptane and/or iso-octane, and a fuel of interest. These fuels of interest were higher octane components; toluene, ethanol, and iso-butanol. A lean condition (Φ = 0.25) with varying intake pressure (atmospheric to 3 bar, abs) and at a constant intake temperature of 155 °C was used to investigate the ignition behavior of all the blends. Two sets of blends consisted of varying percentages of fuels of interest, formulated to approximately have research octane numbers (RON) at 80 and 100. For comparison, neat iso-octane was selected as the representative RON 100 fuel, and (Primary Reference Fuel) PRF 80 blend (20% n-heptane, 80% iso-octane, %v/v) was selected as the representative RON 80 fuel. The results were deduced based on engine-indicated data and exhaust emissions. It was observed that the blends with a higher percentage of n-heptane showed a stronger tendency to autoignite at lower intake pressures. However, as the intake pressure was increased, the lower reactivity components (in this study the high-octane components toluene, ethanol, and iso-butanol) hindered the radical formation in the low-temperature regime and/or delayed the onset of high-temperature heat release. The heat release analysis revealed that the higher-octane components in the blends reduced the low-temperature reactivity of n-heptane and iso-octane as the intake pressure was increased. In addition, distinctively different low-temperature heat release patterns were observed for blends consisting of alcohols and toluene as the intake pressure was increased, confirming distinctively different reaction mechanisms as well as inter component interactions in the blends.

    更新日期:2017-09-14
  • Evaluation of Acid Fracturing Treatments in Shale Formation
    Energy Fuels (IF 3.091) Pub Date : 2017-09-13
    Tiankui Guo, Yanchao Li, Yong Ding, Zhanqing Qu, Naicheng Gai, Zhenhua Rui

    Hydraulic fracturing by stimulated reservoir volume (SRV) is a necessity to realize commercial development of shale gas, and its stimulation mechanism still needs further study, and the effectiveness of supplementary stimulation measures needs further exploration. The shale always contains some carbonate minerals. This paper tests the permeability of acid-etched fracture in shale to explore the influence of carbonate mineral content, acid fluid types and concentration, fracture plane roughness, proppant, and confining pressure on the acid-etched effects in shale, and uses CT scanning to conduct research on variation of microscopic pore-throat texture in shale before and after acid-etching. The test shows that the roughness of the fracture plane perpendicular to the bedding plane is higher than the roughness of that paralleled to the bedding plane, and the roughness in both fracture planes perpendicular to and paralleled to the bedding plane increases as the carbonate minerals content increases. In same group of shale samples, the permeability of self-propped fracture before and after acid-etching respectively is positively correlated with the fractal dimension of the fracture plane before and after acid-etching, and the variation of permeability of self-propped fracture before and after acid-etching is also positively correlated with the variation of fractal dimension of fracture plane before and after acid-etching, which is not shown in different groups of shale samples. When the content of carbonate minerals in shale is between 10% and 30%, the relation between optimum HCL concentration and carbonate mineral content is expressed as Y(OptimumHCLconcentration) = −0.5X(Carbonatemineralcontent) + 0.15. If the shale has a high carbonate mineral content (>30%), the effect of acid-etching is not easily controlled, so the technique of acid fracturing should be carried out cautiously. The permeability of single-layer proppant and self-propped fracture after acid-etching conforms to Walsh theory within certain pressure, and variation and migration of curve slope reflects unstable arrangement, imbedding, and crush of proppant, and nonreactive filled impurity of clay and quartz desquamated and migrated, which coincides well with constant variation of permeability. Applying proper acid fluids and optimum concentration in shale with varying carbonate contents will increase pore size, fracture width, and fracture number. For the shale with abundant calcite-cemented fractures, the optimum acid fluid concentration should be increased properly. Due to ultralow permeability of the matrix in shale, even high concentration acid fluid could not penetrate the core with barren natural fractures or calcium-filled fractures. The results of research provide valuable information for design of acid fracturing in shale play.

    更新日期:2017-09-14
  • Molecular Simulation of the Catalytic Cracking of Hexadecane on ZSM-5 Catalysts Based on Reactive Force Field (ReaxFF)
    Energy Fuels (IF 3.091) Pub Date : 2017-09-13
    Zhuojun Chen, Peng Zhao, Ling Zhao, Weizhen Sun

    Fluid catalytic cracking (FCC) is one of the most dominant processes for heavy feedstock conversion. By using ReaxFF dynamic simulations, the catalytic pyrolysis of hexadecane was investigated with the presence of ZSM-5, hydrated ZSM-5, and hydrated Al/ZSM-5 catalysts under high temperatures. Multimolecular simulation results showed that the hydrated ZSM-5 catalyst has good catalytic reactivity at higher temperatures, and the surface hydroxyl group could promote the yield of ethylene. The hydrated Al/ZSM-5 catalyst was more suitable for the production of small molecules under lower temperatures, and the introduction of aluminum would increase the yield of C3∼C4 and prevent the formation of C–O bonds. The unimolecular simulations confirmed that the introduction of aluminum in the hydrated Al/ZSM-5 catalyst would be beneficial to the dehydrogenation of reactant molecules. Thermal stability simulations of catalysts revealed that the introduction of aluminum into the ZSM-5 catalyst could stabilize the Si–O structure and inhibit the formation of a C–O bond.

    更新日期:2017-09-14
  • Enhancing the Stability of Foam by the Use of Nanoparticles
    Energy Fuels (IF 3.091) Pub Date : 2017-09-13
    Zuhair AlYousef, Mohammed Almobarky, David Schechter

    Foam generation is one of the most promising techniques to overcome gas mobility challenges and improve the sweep efficiency of reservoir fluids. The synergistic effect of surfactant and nanoparticles can help produce a stronger and more stable foam in reservoir porous media. The objective of this work is to assess the ability of anionic surfactant and a mixture of the surfactant and nanoparticles to produce foam for gas mobility control and the enhancement of oil recovery. Static, dynamic, and core flood tests were conducted to evaluate foam strength. Static foam tests in the presence of crude oil showed a clear trend on foam behavior when solid nanoparticles were added to surfactant. As the concentration of nanoparticles increases, the foam half-life increases, too. Foamability tests in Bentheimer sandstone showed better foam generation and stabilization when nanoparticles were used. The addition of nanoaprticles to surfactant solutions resulted in higher pressure drop and, therefore, higher reduction of gas mobility compared to surfactant. The rise in temperature from 25 to 50 °C reduces the measured pressure drop across the core samples in the absence and presence of nanoparticles, which can be attributed to the reduction in foam stability and strength. Both surfactant and a mixture of surfactant and nanoparticles were able to enhance oil recovery. The surfactant was able to bring the oil recovery to 41.45% of the original oil in place (OOIP). In contrast, the presence of nanoparticles resulted in higher oil recovery, 49.05%, of the OOIP.

    更新日期:2017-09-14
  • Method for Isolation and Detection of Ketones Formed from High-Temperature Naphthenic Acid Corrosion
    Energy Fuels (IF 3.091) Pub Date : 2017-09-13
    Logan C. Krajewski, Vladislav V. Lobodin, Winston K. Robbins, Peng Jin, Gheorghe Bota, Alan G. Marshall, Ryan P. Rodgers

    Corrosion control at refineries remains a challenge because the mechanism of naphthenic acid (NAP) corrosion is still not fully understood. The rate of NAP corrosion does not correlate with acidity (as measured by total acid number); therefore, it has been suggested that a subset of NAP in petroleum fractions may be more corrosive than others. Because the primary corrosion product (iron naphthenates) may thermally decompose to ketones at corrosion temperatures (250–400 °C), ketones in corrosion fluids could potentially be used to implicate specific problematic acids in corrosion tests. To that end, we have developed a method for isolating and characterizing ketones in corrosion test solutions. Ketones from tests on palmitic and 4-cyclohexyl pentanoic acids (C16H32O2 and C11H20O2) have been successfully isolated with a strong anion exchange solid-phase separation. Gas chromatography/mass spectrometry identifies ketones formed as a result of model acid corrosion. Fourier transform ion cyclotron resonance mass spectrometry further confirms the detection of these ketones and structurally confirms ketones by use of a commercially available reagent that targets ketones and aldehydes. Additional oxygen species generated in the corrosion test likely result from reactions between dissolved atmospheric oxygen and the mineral oil matrix. With this method now validated, it can be applied in future studies of more complex acid mixtures to determine any structural specificity in naphthenic acid corrosion.

    更新日期:2017-09-14
  • Catalytic Combustion of Heavy Oil in the Presence of Manganese-Based Submicroparticles in a Quartz Porous Medium
    Energy Fuels (IF 3.091) Pub Date : 2017-09-13
    Andrey V. Galukhin, Mohammed A. Khelkhal, Alexey V. Eskin, Yuri N. Osin

    We synthesized manganese oxide(II) submicroparticles stabilized with oleic acid and used them as oil-dispersible catalyst precursor promoting a heavy oil oxidation process. Size, morphological properties, as well as composition of the catalyst were studied in depth by X-ray phase diffraction analysis, thermogravimetric–mass spectrometry analysis, scanning electron microscopy, energy dispersive X-ray analysis, and nitrogen adsorption measurements. We applied nonisothermal kinetic analysis coupled with an isoconversional approach to study the influence of catalyst on the combustion process and showed that Mn-based submicroparticles accelerate predominantly the high-temperature oxidation process.

    更新日期:2017-09-14
  • Iron- and cobalt-doped ceria-zirconia nanocomposites for catalytic cracking of naphtha with regenerative capability
    Energy Fuels (IF 3.091) Pub Date : 2017-09-13
    Oluwole Olagoke Ajumobi, Oki Muraza, Idris A Bakare, Adnan M. Al-Amer

    A series of nano-sized iron- and cobalt-doped ceria-zirconia nanocomposites was prepared using hydrothermal synthesis technique at 180 °C for 24 h, with the successful novel incorporation of both Co and Fe on ceria-zirconia, for n-hexane catalytic cracking. Effects of dopant ions on the improvement of intrinsic properties of ceria-zirconia nanocomposites were investigated using disparate characterization techniques. The synthesized ceria-zirconia nanocomposites exhibited similar x-ray diffraction (XRD) patterns, indicating full fusion of the metal ions into the ceria-zirconia lattice structure. The synthesized nanocomposite catalysts were tested for n-hexane cracking over 10 h time-on-stream, with no previous study or report for catalytic cracking of hexane via ceria-zirconia nanocomposites. Relatively high ethylene and propylene selectivity (both > 62%), was obtained over CZ, FeCoCZa and FeCoCZb over time-on-stream. Comparatively, best catalytic activity and stability was exhibited by FeCoCZa with higher n-hexane conversion. Temperature and catalyst weight per feed flowrate (W/F) variations were investigated using the best catalyst (FeCoCZa). Higher conversions were obtained at higher temperature and lower W/F but varied product selectivity and yield, over time-on-stream. In addition, the spent catalysts were successfully regenerated after catalytic testing via calcination at 600 °C for 4 h, and re-used for two additional cycles.

    更新日期:2017-09-14
  • Co-pyrolysis of mixed plastics and cellulose: An interaction study by Py-GC×GC/MS
    Energy Fuels (IF 3.091) Pub Date : 2017-09-13
    Nanta Sophonrat, Linda Sandström, Ann-Christine Johansson, Weihong Yang

    Understanding of interaction between cellulose and various plastics is crucial for designing waste-to-energy processes. In this work, co-pyrolysis of polystyrene (PS) and cellulose was performed in a Py-GC×GC/MS system at 450°C – 600°C with ratios 70:30, 50:50, 30:70. Polypropylene (PP), polyethylene (PE) and polyethylene terephthalate (PET) were then added to the mixture with different ratios. It was found that co-pyrolysis of PS and cellulose promotes the formation of aromatic products with a large increase in the yield of ethylbenzene as compared to the calculated value from individual feedstock. This indicates interactions between cellulose and PS pyrolysis products. Observations from experiments including more than one type of plastics indicate that the interactions between different plastics are more pronounced than the interaction between plastics and cellulose.

    更新日期:2017-09-14
  • Effect of Ethanolysis on the Structure and Pyrolytic Reactivity of Zhaotong Lignite
    Energy Fuels (IF 3.091) Pub Date : 2017-09-13
    Zhan-Ku Li, Xian-Yong Wei, Hong-Lei Yan, Zhi-Min Zong

    Lignite ethanolysis is one of efficient conversion processes. In our previous study, Zhaotong lignite (ZL) from Southwest China was subjected to ethanolysis to afford ethanol-soluble portion and ethanolyzed residue (ER). The structural features of ZL and ER were investigated by ruthenium ion-catalyzed oxidation (RICO) and Fourier transform infrared (FTIR) spectrometry. The pyrolytic reactivities of ZL and ER were examined with a thermogravimetric analyzer and Curie-point pyrolyzer-gas chromatograph/mass spectrometer. The results show that both ZL and ER are rich in –CH2CH2– and –CH2CH2CH2– bridged linkages connecting aromatic rings. Comparing with the RICO of ZL, the RICO of ER produced much less long-chain alkanoic acids and alkanedioic acids, suggesting that long alkylene bridges and alkyl side chains in ZL were largely cleaved via ethanolysis. Interestingly, ZL has higher condensation degree than ER, which was confirmed by RICO and solid-state 13C nuclear magnetic resonance analysis. The result was explained by ethanolysis simulation of lignite-related model compounds using density functional theory. Thermogravimetric analysis of ZL and ER exhibits their different pyrolytic reactivities. According to analysis with a Curie-point pyrolyzer-gas chromatograph/mass spectrometer, significant differences in the distributions of the volatile species from the pyrolyses of ZL and ER were observed. Guaiacols and carbazoles are the most abundant group components from the pyrolyses of ZL and ER, respectively. ZL pyrolysis released much more alkanes and phenolic compounds than ER pyrolysis. The cleavage of Car–O bonds significantly proceeded during ZL ethanolysis.

    更新日期:2017-09-14
  • Pyrolysis of a Low Asphaltene Crude Oil under Idealized in Situ Combustion Conditions
    Energy Fuels (IF 3.091) Pub Date : 2017-09-13
    Qianghui Xu, Hang Jiang, Desheng Ma, Xi Chen, Jia Huang, Lin Shi

    The coke formation is crucial to the crude oil in situ combustion (ISC) process. This study provided some insights through analyzing the influences of temperature and reaction atmosphere on the coke chemical–structural property. Thin coke films were produced on the polished single-crystal Si surface from the Xinjiang crude oil. Their functional groups were compared by Fourier transform infrared spectroscopy (FTIR), while the nanostructures were characterized through Raman spectroscopy, X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HRTEM) techniques. In addition, the low-temperature oxidation (LTO) coke and the pyrolytic coke reactivities were investigated by thermogravimetric analyses. The results indicated that the main carbon structures in the pyrolytic coke were amorphous. No crystallization phenomena, such as the aromatic ring condensation and the planar stacking, were observed within the characteristic ISC pyrolytic temperature range. Despite the pyrolytic coke yield increase with the temperature, almost constant chemical–structural properties were conserved. This study compared the chemical–structural properties of the LTO coke and the pyrolytic coke from the ISC process. The greater oxidation rate of the LTO coke was attributed to the considerable O-containing groups.

    更新日期:2017-09-13
  • Using Sensitivity Analysis and Gradual Evaluation of Ignition Delay Error To Produce Accurate Low-Cost Skeletal Mechanisms for Oxidation of Hydrocarbon Fuels under High-Temperature Conditions
    Energy Fuels (IF 3.091) Pub Date : 2017-09-13
    Alireza Shakeri, Karim Mazaheri, Mohammad Owliya

    Three-dimensional thermo-hydrodynamic analysis of gas turbine combustion chambers is of great importance in the power generation industry to achieve higher efficiency and reduced emissions. However, it is prohibitive to use a comprehensive full-detailed mechanism in their simulation algorithms because of the huge CPU time and memory space requirements. Many reduction approaches are available in the literature to remedy this problem. Here a new approach is presented to reduce large detailed or skeletal mechanisms of oxidation of hydrocarbon fuels to a low-cost skeletal mechanism. The method involves an integrated procedure including a Sensitivity Analysis (SA) and a procedure of Gradual Evaluation of Ignition Error (GEIE). The sensitivity analysis identifies reactions which have less effect on the flame temperature (Tf) and also those with less effect on the NO concentration (XNO). Using the GEIE procedure also identifies reactions that have less effect on the ignition delay time (τign). In this process, three cutoff limits are selected for Tf, XNO, and τign. The procedure is validated and examined for two different hydrocarbon fuels, i.e., methane and kerosene. The detailed mechanism of GRI-3.0 is used for methane, to produce a low-cost skeletal mechanism containing 118 reactions and 39 species. Similarly, a validated skeletal mechanism for kerosene including 382 reactions and 106 species is used to generate a low-cost skeletal mechanism including only 180 reactions and 79 species. The accuracy of the obtained skeletal mechanisms was investigated to predict the ignition delay and the flame temperature for ranges of inlet temperatures (T0) of 1000–1800 K, combustion pressures (pc) of 1.0–30.0 atm, and equivalence ratios (ϕ) of 0.5–2.0 using a homogeneous IGNITION model. In addition, the applicability of the produced mechanisms to predict oxidation parameters such as flame temperature, velocity of burnt gas, concentration of the main fuel species, some minor radicals, and other selected species was investigated and validated for both skeletal mechanisms using homogeneous models PSR and PREMIXED over a range of different T0 (300–1800 K), pc (1.0–30.0 atm), and ϕ values (0.5–2.0). Comparisons show that the two new skeletal mechanisms have a good agreement with similar known base mechanisms but offer a significant gain in terms of computational cost.

    更新日期:2017-09-13
  • Mass Flow Analysis of Mercury Transformation and Effect of Seawater Flue Gas Desulfurization on Mercury Removal in a Full-Scale Coal-Fired Power Plant
    Energy Fuels (IF 3.091) Pub Date : 2017-09-13
    Sheng Su, Lijun Liu, Lele Wang, Syed Shatir A. Syed-Hassan, Fanhai Kong, Song Hu, Yi Wang, Long Jiang, Kai Xu, Anchao Zhang, Jun Xiang

    To understand the mercury speciation and mass flow in a full-scale bituminous coal-fired power plant equipped with a selective catalytic reduction (SCR) unit, an electrostatic precipitator (ESP), and a seawater flue gas desulfurization (SWFGD) scrubber, the evolution and emission of mercury was systematically measured and analyzed. The results showed that the elemental mercury (Hg0) was oxidized mainly through heterogeneous oxidation, especially in SCR, which transformed 57–64% of elemental mercury (Hg0) to oxidized mercury (Hg2+). It changed the concentrations of different mercury species and then increased the Hg2+ removal efficiencies of SWFGD, which ranged from 67 to 82%. A total of 8.24–11.54% of mercury was adsorbed by fly ash to form particulate-bound mercury (HgP) and subsequently removed by the ESP. Mass flow and mass distribution of mercury indicated that most mercury was removed and retained in the SWFGD. The heterogeneous oxidation of Hg0 in SCR and then absorption of Hg2+ by SWFGD significantly enhanced the mercury removal in the studied coal-fired power plant, although a part of Hg2+ absorbed in SWFGD was reduced and released back to the flue gas. Hg2+ was a little more than Hg0 in the flue gas emitted to the atmosphere. In addition, the SWFGD system without limestone addition may be beneficial for decreasing the re-emission of Hg0. The mercury emission factor at the power plant is 4.098 g/TJ, which is lower than that at other power plants without SCR. The configuration of SCR + ESP + SWFGD enhances the co-benefit mercury control.

    更新日期:2017-09-13
  • Auto-Catalytic Depolymerization of Alkali Lignin by Organic Bound Sodium in Supercritical Ethanol
    Energy Fuels (IF 3.091) Pub Date : 2017-09-12
    Daliang Guo, Bei Liu, Yanjun Tang, Junhua Zhang, Xinxing Xia

    In order to study the catalytic depolymerization process of alkali lignin by organic bound sodium in supercritical ethanol, the solid chars and liquid oils products were firstly prepared by using a high pressure autoclave at different temperatures and times. Then the properties of solid chars were analyzed by elemental analysis, FT-IR and SEM, and the composition of liquid oils was characterized by GC-MS. FT-IR and SEM results showed that the depolymerization process of alkali lignin catalyzed by organic bound sodium in sub- and super-critical ethanol formed different micron-sized spheres products, and the sphere size of the char products was obviously affected by the depolymerized temperature. The C/O and C/H ratios of the chars products also increased with depolymerized temperature increasing. GC-MS results indicated that the components of liquid oils obtained from sub- and super-critical ethanol mainly were ester and phenolic compounds, respectively.

    更新日期:2017-09-13
  • Steam gasification of thermally extracted ash-free coals: reactivity effects due to parent raw coals and extraction solvents
    Energy Fuels (IF 3.091) Pub Date : 2017-09-12
    Lia Priscilla, Yongjin Kong, Jiho Yoo, Ho Kyung Choi, Youngjoon Rhim, Jeonghwan Lim, Sangdo Kim, Dong Hyuk Chun, Sihyun Lee, Young Woo Rhee

    Utilization of coal is currently limited to coal-fired power plants and iron smelting, partly due to incombustible ash in coal and the inability of existing technologies to modify its properties. This work investigates whether the gasification behavior of ash-free coals (AFCs) can be modified. Sixteen different AFCs are prepared using variously ranked coals (Eco, Cyprus, Drayton, and Hail Creek) and extraction solvents with different polarities (N-methyl-2-pyrrolidone, ethylenediamine, 1-methylnaphthalene, and tetralin). Next, the reactivity of the AFCs with steam gasification at 800 ºC is tested and discussed taking into consideration their compositional differences. A combination of low-rank coals and polar solvents produces reactive AFCs, which can be catalytically gasified under mild conditions. In contrast, AFCs extracted using non-polar solvents are less reactive and possibly applicable as a carbon electrode precursor. In short, the properties of AFCs can be changed to some extent using the appropriate combination of coals and extraction solvents.

    更新日期:2017-09-13
  • Organic matter characterization of shale rock by X-ray Photoelectron Spectroscopy (XPS): adventitious carbon contamination and radiation damage
    Energy Fuels (IF 3.091) Pub Date : 2017-09-12
    Antonela Canneva, Iván Santiago Giordana, Georgina Erra, Alejandra Calvo

    A detailed characterization of the organic matter in sediments gives a key parameter for a correct evaluation of the petroleum generation potential of a source rock and its modeling in an oil system. To understand the features of the organic matter stored in source rocks, a wide variety of routine techniques are used. Those techniques are mostly destructive, time consuming and are not necessarily suitable for all the shale rocks. Thus, new technologies are being explored. XPS is a solid state, non-destructive and direct method. It can be used to directly probe the speciation of organic carbon in sedimentary materials by C1s spectra measurements. In this work, we demonstrated that a heterogeneous layer of adventitious carbon (AC) is always present on the rock. This layer significantly altered the features of the organic compounds fingerprint, which is measured by XPS of C1s. To acquire a reliable organic matter composition of a rock from XPS spectra it is necessary to remove the AC layer by sputtering by Ar+. Further, sputtering damage of organic matter appears after an hour of radiation and rocks become contaminated again during storage in the UHV chamber. The radiation damage by X-ray is also relevant in the XPS measurement of a rock. This damage is associated to an increment of AC contamination on the rock surface. To minimize this side effect, C1s spectra have to be measured immediately after the sputtering conditioning step. Thus, we developed a method for XPS measurements taking into account the AC contamination and radiation damages. We consider that the proposed method for outcrops shales can be applied to a wide range of rock sampling types, such as: cuttings, damaged crowns, etc.

    更新日期:2017-09-12
  • Biocatalyzed accelerated post combustion CO2 capture and stripping in monoethanolamine
    Energy Fuels (IF 3.091) Pub Date : 2017-09-12
    Prakash C. Sahoo, Manoj Kumar, Amardeep Singh, Mahendra P. Singh, Suresh K. Puri

    The existing solvent mediated CO2 capture process is energy intensive due to high temperature requirement for solvent regeneration. Therefore, improvement of solvent systems for optimized and low energy intensive CO2 capture and desorption is of enormous interest. In this regard, we report a novel matrix composed of ZnO/Fe2O3 encapsulated mesoporous silica tethered thermostable carbonic anhydrase (CA) (designated as CA@fn-Zn/Fe/MS). The enzyme coupled matrix was used for efficient post combustion CO2 capture and low energy intensive desorption. It was observed that the use of CA@fn-Zn/Fe/MS (0.5 wt%) in 30% Monoethanolamine (MEA) enhances the CO2 uptake to 0.82 mol/mol of solvent and the regeneration efficiency by 2.6 times as compared to the neat MEA at 30 wt% . The enzyme coupled matrix is stable over a broad range of pH and can be used for several cycles. The development adds values to improve conventional amine based CO2 scrubbing technology.

    更新日期:2017-09-12
  • Absorption of nitrogen oxides into sodium hydroxide solution in a rotating packed bed with pre-oxidation by ozone
    Energy Fuels (IF 3.091) Pub Date : 2017-09-12
    Baochang Sun, Miaopeng Sheng, Wenlei Gao, Liang-Liang Zhang, Moses Arowo, Yan Liang, Lei Shao, Guang-wen Chu, Haikui Zou, Jian-Feng Chen

    This study employed a rotating packed bed (RPB) to enhance the absorption performance of Nitrogen Oxides (NOx) into sodium hydroxide (NaOH) solution with the pre-oxidation of NO by ozone. The absorption performance of NOx was evaluated in terms of its removal efficiency (η) from a gas stream under various operating conditions including O3/NOx molar ratio (MR), rotation speed of the RPB (N), liquid flow rate (L), NaOH concentration (CNaOH), inlet NOx concentration (CNOx) and using time (t). Also, the corresponding effect of adding oxidants (NaClO, H2O2 and KMnO4) and a reductant (CO(NH2)2) into the NaOH solution on NOx removal efficiency was investigated. Results indicated that pre-oxidation of NO by O3 significantly improved NOx removal efficiency and the removal efficiency increased with increasing O3/NOx molar ratio, NaOH concentration and liquid flow rate but decreased with increase in inlet NOx concentration and using time. Additionally, NOx removal efficiency firstly increased and then decreased with increasing rotation speed of the RPB. Both the oxidation and reduction additives enhanced NOx removal efficiency and the order of enhancement was found to be KMnO4> H2O2> CO(NH2)2 >NaClO. These results further indicate that the hydrolysis reactions of NOx are the rate-determining steps in NOx absorption process, and thus, the main factors hindering NOx removal during wet scrubbing process. This work demonstrates that RPB has great potential for removal of NOx by wet scrubbing process in view of the small size of the RPB, low temperature and the short gas retention time of 0.27 s applied in this work.

    更新日期:2017-09-12
  • Long-term dynamics of microbial communities in a high-permeable petroleum reservoir reveals the spatio-temporal relationship between community and oil recovery
    Energy Fuels (IF 3.091) Pub Date : 2017-09-12
    Zhiyong Song, Fengmin Zhao, Gangzheng Sun, Weiyao Zhu

    To assess the dynamics of microbial communities in a petroleum reservoir during microbial enhanced oil recovery (MEOR), injected and produced fluids from multiple wells were monitored using molecular microbial methods over 20 months. In this highly-permeable (1.5–2.5 μm2) and high-temperature (65°C) reservoir, communities contains phyla Euryarchaeota, Proteobacteria, Deferribacteres, and Firmicutes, which may be collected by flooding fluids from different habitats through strata. Since the oil-rich areas in the flooded reservoir generally gather around oil wells with high temperatures and strictly anaerobic conditions, the dominance of thermophilic and anaerobic microorganisms, which are capable of inhabiting oil-rich areas, is consistent with positive oil-output responses (temporarily enhanced by 5 ×103 kg per day). During later periods, the communities were dominated by Enterobacter without high-temperature adaptability, which corresponds to a considerable decline in oil-output. Meanwhile, an abnormal increase of community similarity, acetate, and cell concentrations in produced fluids simultaneously indicated a severe enhancement of reservoir permeability along the flooding route, which reveals the direct reason of the community shift and the oil output decline. Therefore, an understanding of the long-term dynamics of reservoir communities is essential for distinguishing functional species and to establish a reservoir-scale connection between microbiology and porous flow.

    更新日期:2017-09-12
  • Mercury re-emission in the smelting flue gas cleaning process: the influence of arsenite
    Energy Fuels (IF 3.091) Pub Date : 2017-09-12
    Zhilou Liu, Dongli Wang, Bing Peng, Liyuan Chai, Shu Yang, Cao Liu, Cong Zhang, Xiaofeng Xie, Hui Liu

    Recently, the Hg0 re-emission from flue scrubbing solutions has become a research focus. The objective of this study was to evaluate the influence of arsenite on Hg0 re-emission by investigating critical important parameters, including the arsenite ion concentration, pH values, solution temperature, fluorine ion concentration, and chlorine ion concentration. The experimental results indicate that arsenite could directly reduce Hg2+ to Hg0 and promote the decomposition of Hg(SO3)22-. High pH, temperature and chlorine ion concentration contributed to the inhibition of Hg0 re-emission, but the fluorine ions had little effect. The mechanism research suggests that the formation of unstable HgH2AsO3+ at low arsenite concentration accelerates Hg0 re-emission. For the Hg(II)-As(III)-S(VI) system, the formation of unstable HgSO3H2AsO3- than Hg(SO3)22- could increase Hg0 re-emission. With an increase in arsenite concentration, the formation of Hg(H2AsO3)2 (which comes from the reaction between HgSO3H2AsO3- and H2AsO3-) contributes to the suppression of Hg0 re-emission. The results of this study are conducive to providing new insight into Hg0 re-emission and mercury control.

    更新日期:2017-09-12
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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