显示样式:     当前期刊: Energy & Fuels    加入关注    导出
我的关注
我的收藏
您暂时未登录!
登录
  • Characteristics of CaS–CaO Oxidation for Chemical Looping Combustion with a CaSO4-Based Oxygen Carrier
    Energy Fuels (IF 3.091) Pub Date : 2017-11-20
    Min Zheng, Simei Zhong, Kongzhai Li, Hua Wang, Huili Liu, Yonggang Wei, Xing Zhu

    The oxidation of CaS to a CaSO4 oxygen carrier suffers SO2 release. To capture SO2 released, an amount of CaO particles was mixed with CaS particles. Isothermal kinetics of the CaS–CaO oxidation reaction has been conducted in a thermogravimetric reactor combined with a Frourier transform infrared spectroscopy (FTIR) analyzer. The effects of the reaction temperature, O2 concentration, and molar ratio of CaO/CaS on CaSO4 generation and SO2 emission were investigated. The chemical compositions, morphology structures, and element distributions on the surfaces of solid residuals were characterized by FTIR and scanning electron microscopy–energy-dispersive X-ray spectroscopy instruments. The results show that the oxidation products of CaS species are mainly composed of CaSO4. A small amount of SO2 is released from CaS oxidation, causing losses of the oxygen carrying capacity of a CaSO4-based oxygen carrier. Using a CaO additive in the CaS oxidation process reduces SO2 liberation, improves the CaSO4 selective yield, but results in an increase in remaining CaS species in solid residues. There is a general positive correlation between the remaining percentage of CaS species and the SO2 selective yield. The SO2 liberation varies with the reaction temperature, O2 concentration, and CaO/CaS molar ratio. At 900 °C, a CaO/CaS molar ratio of 1, and 5% O2, SO2 released from CaS oxidation is completely trapped by the CaO additive.

    更新日期:2017-11-20
  • Enhancement of Mercury Removal Efficiency by Activated Carbon Treated with Nonthermal Plasma in Different Atmospheres
    Energy Fuels (IF 3.091) Pub Date : 2017-11-20
    Peng Hu, Yufeng Duan, Weike Ding, Jun Zhang, Liyi Bai, Na Li, Hongqi Wei

    To enhance the performance of activated carbon (AC) for elemental mercury removal, a kind of AC was modified by nonthermal plasma (NTP) and the effects of the modification of the atmosphere (N2, O2, air, and HCl) were investigated by adsorption and desorption experiments. The physical and chemical properties of original and modified ACs were characterized by Brunauer–Emmett–Teller, scanning electron microscopy with energy-dispersive spectroscopy, and X-ray photoelectron spectroscopy (XPS). The results showed that better mercury removal performance of ACs was obtained after modifying by NTP in air, O2, and HCl. The mercury removal efficiency of AC–air, AC–O2, and AC–HCl was obviously enhanced compared to the raw AC and AC–N2 attributed to the large increase of oxygen-containing functional groups [C═O and C(O)–O–C] occurring on the AC surface. AC treated in HCl could form C–Cl groups, which were beneficial to improve its oxidizing ability. In addition, stronger etching and cracking on the AC surface during NTP modification in an O2 or a HCl atmosphere were found to decrease its specific surface area and micropore volume, resulting in an adverse effect on mercury removal. It was found that the desorption peaks at 290 and 340 °C of the adsorbed AC samples corresponded to carbonyl groups (C═O) and ester groups [C(O)–O–C], respectively, which were verified by combining the results of XPS and temperature-programmed desorption experiments.

    更新日期:2017-11-20
  • Flocculation of Particulates in Fluid Catalytic Cracking Slurry Oil: Characterization of the Particulates and the Effect of Thermal Treatment on Their Flocculation
    Energy Fuels (IF 3.091) Pub Date : 2017-11-20
    Cunhui Lin, Jingqi Wang, Zongxian Wang, He Liu, Kun Chen, Aijun Guo, Tianping Xia

    Removal of particulates in slurry oil (SO) from the fluid catalytic cracking process is a challenging task in refining. In this study, we investigate the intrinsic characteristics of particulates in SO and the effect of thermal treatment on their flocculation and further separation. The particulates in SO were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, etc. Results show that the particulates in SO are composed of coke powders and catalyst powders coated with coke species, with diameters of approximately 1 μm dominating the particle size distribution. The solid contents of middle fractions depend upon thermal treating severities. The particulates are originally dispersed in SO, whereas flocculation of particulates is observed after thermal treatment. A negative linear correlation is found between the solid contents of middle fractions and the asphaltene contents of thermally treated SOs under different thermal treating severities. The mechanism of particle growth as a result of flocculation of particulates with asphaltenes, which favors efficient removal of particulates, is proposed.

    更新日期:2017-11-20
  • Advances in Asphaltene Petroleomics. Part 1: Asphaltenes Are Composed of Abundant Island and Archipelago Structural Motifs
    Energy Fuels (IF 3.091) Pub Date : 2017-11-20
    Martha L. Chacón-Patiño, Steven M. Rowland, Ryan P. Rodgers

    For decades, discussion of asphaltene structure focused primarily on molecular weight. Now that it is widely accepted that asphaltene monomers are between ∼250 and 1200 g/mol, disagreement has turned to asphaltene architecture. The classic island model depicts asphaltenes as single core aromatic molecules with peripheral alkyl side chains, whereas the less widely accepted archipelago model, includes multiple aromatic cores that are alkyl-bridged with multiple polar functionalities. Here, we analyze asphaltene samples by positive-ion atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry and perform infrared multiphoton dissociation to identify their aromatic core structures to shed light on the abundance of island and archipelago structural motifs. Our results indicate that island and archipelago motifs coexist in petroleum asphaltenes, and unlike readily accessible island motifs, asphaltene purification is required to detect and characterize archipelago species by mass spectrometry. Moreover, we demonstrate that mass spectrometry analysis of asphaltenic samples is biased toward the preferential ionization/detection of island structural motifs and that this bias explains the overwhelming mass spectral support of the island model. We demonstrate that the asphaltene structure is a continuum of island and archipelago motifs and hypothesize that the dominant structure (island or archipelago) depends upon the asphaltene sample.

    更新日期:2017-11-20
  • Thermogravimetry study of pyrolytic characteristics and kinetics of fast-growing Eucalyptus residue
    Energy Fuels (IF 3.091) Pub Date : 2017-11-20
    Qunpeng Cheng, Meng Jiang, Zhenhua Qin, Shunxi Zhang, Mei Wang, Jianfen Li

    In order to utilize the fast-growing Eucalyptus residue (FGER) for energy application, the pyrolysis kinetic of FGER was studied by a new simple DAEM method through thermo-gravimetry analysis at different heating rates of 10℃/min, 20℃/min, 30℃/min, 40℃/min and 100℃/min from room temperature to 1000℃respectively. The results showed that the DAEM could fit the experimental data well. The pyrolysis weight loss process of FGER could be divided into four stages. The first and second stages attributed to hemicelluloses decomposition located at α= 0-0.1 and α=0.11-0.34 with activation energy of 117kJ/mol and 155.8 kJ/mol, respectively. It was found that cellulose pyrolysis in the third stage, which covered a conversion range of α=0.35-0.74 with E=182.9 kJ/mol. The fourth stage represented the tails of DTG curve and occurred at high conversion with high activation energy value. The DAEM fitted the experiments well in low conversion α<0.8. The weight fraction distribution in fourth stage was complex, which indicated the heterogeneity of reaction.

    更新日期:2017-11-20
  • Phase-Change Absorption of SO2 by Imidazole in Organic Solvents and Conversion of the Absorption Product in the Presence of Water and Oxygen
    Energy Fuels (IF 3.091) Pub Date : 2017-11-20
    Yang Wang, Wenbo Zhao, Muyuan Chai, Genming Li, Qingming Jia, Yuan Chen

    Conventional removal of SO2 yields a large amount of waste salts or requires significant energy use for regeneration of the absorbent. Phase-change capture has been considered a possible method to solve these problems since only the absorption product needs to be disposed for recovery and the solvent could be reused directly. In the present work, the phase-change absorption behavior of 1,3,5-trimethylpyrazole, 2-methylimidazole, 1-methylimidazole, and 1,2-dimethylimidazole has been investigated in organic solvent. Among these compounds, 1,2-dimethylimidazole exhibited an obvious phase-change performance in solvents propylene carbonate, three glycol dimethyl ether and dimethylacetamide, but not in butanol. The composition and structure of the absorption product were not related to the type of solvent but affected by the air. 1,2-dimethylimidazole reacted with SO2 to form a charge-transfer complex, which converted to pyrosulfite, (C5H9N2)2S2O5, in the presence of water. The absorption product was further oxidized to dithionate, (C5H9N2)2S2O6, by oxygen from the air. Once the filtrate, created from the separation process of the phase-change product and solvent, was exposed to air for several days, another type of oxidative product, (C5H9N2)2SO4, was discovered.

    更新日期:2017-11-20
  • Chemical Looping Gasification of Coal in a 5 kWth Interconnected Fluidized Bed with Two-stage Fuel Reactor
    Energy Fuels (IF 3.091) Pub Date : 2017-11-20
    Tianxu Shen, Jian Wu, Laihong Shen, Jingchun Yan, Shouxi Jiang

    Abstract Chemical looping gasification (CLG) is a novel technology using lattice oxygen in solid oxygen carrier (OC) for syngas production. The present work investigated the CLG performance of coal in a 5 kWth interconnected fluidized-bed, in which fuel reactor was designed as a two-stage based circulating bed. The fresh OC from air reactor entered into the upper stage of fuel reactor, in which it was reduced by syngas. Then, the partial reduction of OC was circulated to the bottom stage of fuel reactor to be reduced further to low valence metal oxide and catalyze the process of coal gasification. Afterwards, the reduced OC was transported to air reactor for regeneration. The influences of coal feeding rate, gasification temperature and gasification agent on the performance of CLG were evaluated in detail. The syngas yield and gasification efficiency were remarkably influenced by coal feeding rate with an optimal value of 487.5 g/h in the current unit. The high temperature promoted the coal gasification process with the maximum gasification efficiency and syngas yield corresponding to 75.2% and 0.97 Nm3/ (kg• coal) respectively at gasification temperature of 915 ℃. Steam, CO2 and mixture of them were used as gasifying agent separately. The experiment results demonstrated that carbon conversion, syngas yield and gasification efficiency increased with the proportion of steam in gasifying agent. The OC particles in the upper and bottom stages of fuel reactor were analyzed by XRD. The main phase of the OC particles in the bottom stage was FeO, which has a high catalytic activity on coal gasification and tar cracking. Serious particle agglomeration was observed under the low fluidization flow of 20 L/min and high temperature of 950 ℃ at which the system cannot be stable operated. Keywords: Chemical looping gasification; Two-stage circulating bed; Gasifying agent; Oxygen carrier

    更新日期:2017-11-20
  • Pure and binary gas adsorption equilibrium for CO2-N2 on oxygen enriched nanostructured carbon adsorbents
    Energy Fuels (IF 3.091) Pub Date : 2017-11-19
    Chitrakshi Goel, Deepak Tiwari, Haripada Bhunia, Pramod K. Bajpai

    Pure component (CO2 and N2) adsorption isotherms of oxygen enriched nanostructured carbon (RF-700) were evaluated using a static volumetric analyzer at four different adsorption temperatures ranging from 30 to 100 °C. Langmuir, Sips, and dual-site Langmuir (DSL) models were used to correlate pure component adsorption isotherms and it was found that Sips and DSL isotherm model fitted well with the experimental data, indicating heterogeneous nature of the adsorbent surface. Fixed-bed column was used to obtain dynamic breakthrough data for binary system CO2-N2 at different adsorption temperatures (30-100 °C) and CO2 feed concentrations (5-12.5% by volume). Extended Sips, Extended DSL and IAST (ideal adsorbed solution theory) models using pure component adsorption isotherm data, were used for the prediction of adsorption of binary system (CO2-N2). Predicted equilibria data was compared with experimental breakthrough curve data and it was found that extended forms of the isotherm models (Sips and DSL) under-predicted CO2 adsorption equilibria because of difference in adsorptive strengths of CO2 and N2 molecules. Ideal adsorbed solution theory failed to describe the mixed-gas adsorption equilibria. Asymmetric x-y diagrams showed positive deviation from Raoult’s law. Feasibility of the adsorption process was suggested by negative value of molar Gibbs free energy change. Formation of more ordered configuration of CO2 molecules on adsorbent surface was seen as higher heat of adsorption was exhibited for CO2 as compared to N2.

    更新日期:2017-11-20
  • Mass Transfer Performance for CO2 Absorption by 2-((2-aminoethyl)amino) ethanol Solution in Rotating Packed Bed
    Energy Fuels (IF 3.091) Pub Date : 2017-11-19
    Shu-ying Wu, Liang-Liang Zhang, Baochang Sun, Haikui Zou, Xiaofei Zeng, Yong Luo, Qiang Li, Jian-Feng Chen

    The emission of CO2 leads to serious global climate change, which has attracted increasing attention. In this work, rotating packed bed (RPB) was employed as a high effective reactor to intensify the CO2 absorption in alkanolamine solution, which mainly contained 2-((2-aminoethyl)amino) ethanol (AEEA). The effects of important operation conditions, such as high gravity level, amine solvent concentration, gas-liquid flow ratio, CO2 inlet concentration, absorption temperature and CO2 loading in amine solvent, on gas-phase volumetric mass transfer coefficient (KGa) and CO2 capture efficiency were investigated. Results indicated that the high gravity level and CO2 inlet concentration had significant effects on KGa, and the experimental value of KGa was about 1.42-2.86 kmol∙m-3∙h-1∙kPa-1 in RPB, which was an order of magnitude higher than that in a conventional packed column. Furthermore, an artificial neural network (ANN) model was applied to predict the mass transfer performance. The predicted values from the ANN model were in good agreement with experimental data (±10%).

    更新日期:2017-11-20
  • Investigation of corrosion characteristics of high-sodium high-chlorine lignite during circulating fluidized bed combustion
    Energy Fuels (IF 3.091) Pub Date : 2017-11-19
    Xiaobin Qi, Guoliang Song, Shaobo Yang, Zhao Yang, Qinggang Lu

    Corrosion experiments were conducted in a 0.4 T/D circulating fluidized bed (CFB) test rig with the high-sodium high-chlorine lignite as fuel to investigate the corrosion phenomena and mechanisms through the air-cooled probes in furnace and tails, respectively. Three alloy materials involving four metal elements (Al, Cr, Ni and Fe) were used to compare their anticorrosion characteristics with the thermodynamic equilibrium calculation software Factsage 6.1 as an auxiliary tool. Experimental results indicate that the probes exposed to the high-temperature flue gas in furnace suffered severe corrosion, which was primarily caused by gaseous corrosive media including HCl (g), NaCl (g) and Cl2 (g), while the probes in tails underwent the almost negligible corrosion arising from the deposited NaCl crystal on the top surface of the probe. The protective oxidation scale formed on the outer surface of alloy was the key to corrosion resistance rather than the internal metal with high quality. Despite different alloy elements match different corrosive environments for its optimal anticorrosion, the Al2O3 was found most effective to resist the chlorine-induced corrosion in this study. According to the Gibbs free-energy change (Delta G) of corrosion reactions, the increasing temperature failed to reduce the difficulty of corrosion in essence. The accelerated corrosion at a higher temperature was mainly ascribed to the improvement of the diffusion of the gaseous corrosive species and gaseous reaction products (metal chlorides). At a low-level wall temperature, to a certain extent the influence of gas temperature and alloy materials on corrosion can be ignored.

    更新日期:2017-11-20
  • Influence of Ethanol and Exhaust Gas Recirculation on Laminar Burning Behaviors of Fuels for Advanced Combustion Engines (FACE-C) Gasoline and Its Surrogate
    Energy Fuels (IF 3.091) Pub Date : 2017-11-17
    Ossama A. Mannaa, Morkous S. Mansour, William L. Roberts, Suk Ho Chung

    Laminar burning velocities of fuels for advanced combustion engines (FACE-C) gasoline and a surrogate comprising toluene primary reference fuels (TPRFs) were investigated under the effects of exhaust gas recirculation (EGR) dilution and ethanol blending. Measurements were conducted in a spherical constant volume combustion chamber for a range of equivalence ratios from 0.8 to 1.6 at initial temperatures and pressures up to 383 K and 0.6 MPa, respectively. These measurements highlighted the effects of real combustion residuals (using combustion products directly) at mole fractions up to 0.3 and various volumetric percentages of ethanol blending. For both studied fuels, significant reductions in stretched and unstretched flame speeds were observed for mixtures laden with real combustion residuals. Blends with less than 50% ethanol showed barely a minimal enhancement in the flame speed. By combining both EGR and ethanol blending, the flame speed reduction by EGR can be compensated for with ethanol addition. For example, up to 10% of EGR requires 60% ethanol blending to maintain the same flame speed. Flame stability enhancement by EGR addition was also quantified through the determination of the Markstein length.

    更新日期:2017-11-19
  • Water Distribution in Overmature Organic-Rich Shales: Implications from Water Adsorption Experiments
    Energy Fuels (IF 3.091) Pub Date : 2017-11-17
    Peng Cheng, Hui Tian, Xianming Xiao, Haifeng Gai, Tengfei Li, Xing Wang

    Exploratory and developmental data show that connate water has a significant effect on the gas content of a shale. On the basis of its mobility in shales, connate water could be classified as free water and irreducible water, and the latter is generally dominant in highly mature or overmature shales. However, it is still not fully understood how the irreducible water is distributed in different nanopores of shales at the overmature stage. In this study, two groups of overmature Lower Paleozoic shale samples from southern China were selected for water adsorption experiments based on the ASTM standard (D1412-07, 2010), and the distribution of irreducible water in different nanopores was investigated. The results show that the equilibrium irreducible water contents for the two sample sets range from 5.4 mg/g rock to 15.58 mg/g rock. Although irreducible water is actually mainly stored in inorganic pores for the most of our shale samples, the equilibrium irreducible water contents of these shales are found to be positively correlated with TOC contents, indicating that irreducible water in shales could be hosted in organic pores as well as in inorganic pores. For a given irreducible water content, the percentages of nonmicropore surface area and pore volume occupied by irreducible water are larger than those of the microspore surface area and pore volume, implying that irreducible water is more easily stored in nonmicropores than in micropores for our overmature shale samples, and that the irreducible water may be mainly stored in an absorbed state in nonmicropores but in a condensed state in micropores. Furthermore, there is still approximately 50% of micropore volume or surface area available for gas adsorption even when the shale sample is equilibrated with absorbed water at a relative humidity of 96–97%. This study provides new data for understanding the distribution of irreducible water in the nanopores of highly mature or overmature shales and is helpful for accurately evaluating the shale gas content under geological conditions.

    更新日期:2017-11-19
  • Influence of Wet Torrefaction Pretreatment on Gasification of Larch Wood and Corn Stalk
    Energy Fuels (IF 3.091) Pub Date : 2017-11-17
    Shumin Fan, Li-Hua Xu, Hueon Namkung, Guangri Xu, Hyung-Taek Kim

    Biomass was wet-torrefied to improve its properties prior to gasification. Two kinds of biomass were employed as feedstock, including the larch wood and corn stalk. For both larch wood and corn stalk, the oxygen content of torrefied samples reduced greatly, while the carbon content increased. All of these features had a positive effect on the gasification process, which was discussed in the research. During steam gasification, all of the wet-torrified biomass samples yielded higher amounts of H2 and CO compared to the raw biomass samples, showing the superiority of the wet torrefaction (WT). During CO2 gasification, the CO production was also significantly improved by WT. The kinetic characteristic parameters for the gasification of raw and torrefied biomass samples were determined using the random pore model. It was found that the activation energy of gasification could be reduced by the WT process.

    更新日期:2017-11-19
  • Investigations on the Ash Deposit Formation of Tubular Air Preheater in a Coal-Fired Traveling Grate Boiler
    Energy Fuels (IF 3.091) Pub Date : 2017-11-17
    Xiaolu Chen, Qinxin Zhao, Zhiyuan Liang

    A study was undertaken of the air preheater ash deposit in a 140 MW coal-fired traveling-grate boiler. Several ash samples were collected in the selected regions of the air preheater along with samples of the feed coal. The ash samples were examined using combination of ash X-ray fluorescence (XRF) and X-ray diffraction (XRD) analysis to determine the chemistry and mineralogy. The ash samples were also examined using scanning electron microscopy and energy dispersive spectrum (SEM-EDS) analysis to determine the microstructure and phase constitution. The analysis results showed that the sulfur content of ash deposits varied with the temperature of the gas flue. The higher amounts of sulfur in ash deposits proved to be sulfates. It appeared that sulfuric acid was a driving factor in the formation of the deposition. The sulfates probably acted as cementing agent, giving the deposit its hardness and thickness.

    更新日期:2017-11-19
  • Estimation of Pores Distribution in Lignite Utilizing Hg, H2O, CO2, and N2 as Molecular Probes
    Energy Fuels (IF 3.091) Pub Date : 2017-11-17
    Qiongqiong He, Yijun Cao, Zhenyong Miao, Xuefeng Ren, Jingpeng Chen

    Pores size distribution (PSD) and surface area (SA) analysis are so important for the description of porous materials, so selection of different pore characterization methods is emphasized, especially nondestruction methods. In this study, N2, H2O, CO2, and Hg were utilized as molecular probes to estimate the PSD in Shengli lignite (SL). In the N2 adsorption, traditional degassed sample and wet samples freezing by liquid N2 were combined to obtain the PSD and moisture distribution in SL. The pores of degassed samples were mainly located in the range of 5–100 nm, and most of the moisture was in the larger macropores in the range of 26–100 nm, peaking at 37 nm. We used two methods of H2O as molecular probe: H2O dynamic adsorption and low-field nuclear magnetic resonance (LFNMR). The saturation concentration of H2O in the pore of SL was 0.29 cm3/g from H2O adsorption, and the pores located in the range of 1–154 nm and peaked at 42.4 nm from LFNMR. The comparison and combination of different molecule probes were also presented. The surface area (SA) from CO2 adsorption was the most credible because of the good monolayer adsorption of CO2 in the micropores. N2 and CO2 adsorption would lead to an underestimation of the mesopore and micropore volume, and LFNMR has the most potential for PSD analysis owing to the high accuracy of the equipment and the nondestructive sample (without predrying process).

    更新日期:2017-11-19
  • Hydrocarbon Generation Kinetics of a Heterogeneous Source Rock System: Example from the Lacsutrine Eocene-Oligocene Shahejie Formation, Bohai Bay Basin, China
    Energy Fuels (IF 3.091) Pub Date : 2017-11-17
    Zhuoheng Chen, Maowen Li, Tingting Cao, Xiaoxiao Ma, Zhiming Li, Qigui Jiang, Zheng Li, Chunqing Jiang

    Source rock heterogeneity is a common and important feature that requires attention in shale oil resource evaluation. The Eocene-Oligocene Shahejie Formation in the Jiyang Superbasin, Bohai Bay Basin, has been studied to investigate vertical variations in source rock characteristics and their thermal decomposition behaviors in relation to lacustrine shale oil resource potential. Fifty-four core samples from Luo 69 Well were analyzed using Rock-Eval 6 equipment, and the resulting FID (flame ionization detector) hydrocarbon pyrograms were examined to study their generation kinetics. Differences in bulk geochemical characteristics, petroleum generation capacities, and petrophysical properties allow for subdivision of the samples into three “homogeneous” groups: (a) a stratigraphically higher facies, corresponding to samples with HI value around 600 mg HC/g TOC and high S1/TOC (due to either exogenous hydrocarbon input or thermally less stable kerogen, or both); (b) stratigraphically a facies in the middle of the section, representing thermally more stable facies group with similar generation potential, but much lower S1/TOC; and (c) a stratigraphically lower facies, corresponding to source rock with low TOC (<2%) and HI (<350 mg HC/g TOC) and high S1/TOC, and thermally less stable organic matter. Such a grouping is consistent with a statistical classification by Principal Component Analysis (PCA) based on the Rock-Eval data set. Bulk generation kinetic parameters from samples in the higher and lower stratigraphic groups seem to be affected by the high S1-associated heavy hydrocarbon residues in default S2 temperature regime. Although the unaffected samples in the middle of the section show “homogeneous” bulk geochemical characteristics in general, the temperature of onset (and offset) of major hydrocarbon generation can vary up to 15 °C among the samples, indicating a kinetically heterogeneous source rock. For a geothermal gradient of 30 °C/km, this translates to a difference of 500 m in burial depth for the onset of hydrocarbon generation for the same source rock unit in the extreme case.

    更新日期:2017-11-19
  • Application of Bacillus spp. in Pilot Test of Microbial Huff and Puff to Improve Heavy Oil Recovery
    Energy Fuels (IF 3.091) Pub Date : 2017-11-17
    Shanshan Sun, Yijing Luo, You Zhou, Meng Xiao, Zhiyong Zhang, Jirui Hou, Xiaofang Wei, Quanshu Xu, Te Sha, Hao Dong, Hao Song, Zhongzhi Zhang

    Microbial metabolic products, such as biosurfactants, bioemulsifiers, acids, solvents, and biogases, are useful for reducing the viscosity of heavy oils and enhancing oil recovery. Two heavy oil viscosity-reducing microorganisms, namely, SH-2 and SH-3, were selected from produced water which were collected from high-temperature reservoirs by enrichment culture technique. The screened bacteria produce biosurfactants and biogases that can biodegrade heavy crude oil components. The screened bacteria combined with indigenous bacteria were applied in a pilot test of microbial huff and puff. Temperature, porosity, and permeability of the reservoir were 50 °C, 14.32%, and 22 mD, respectively. After microbial treatment, the 50 °C degassing for crude oil viscosity of the produced oil was decreased from 750 to 634 mPa·s. Moreover, wax and resin–asphaltene contents of produced oil were reduced by 12.3% and 16.9%, respectively. The average oil production was improved from 2.2 to 3.5 t/day after microbial treatment. The production remained stable without the chemical viscosity reducer for 54 days. The analysis of bacterial community structure indicated that the number of bacteria species increased and that the microbial diversity was highly abundant. However, harmful microorganisms for microbe-enhanced oil recovery, such as sulfate-reducing bacteria, are inhibited during the progress of microbial huff and puff.

    更新日期:2017-11-19
  • Enhanced CO2 Adsorption Performance on Hierarchical Porous ZSM-5 Zeolite
    Energy Fuels (IF 3.091) Pub Date : 2017-11-17
    Qing Liu, Pingping He, Xingchi Qian, Zhaoyang Fei, Zhuxiu Zhang, Xian Chen, Jihai Tang, Mifen Cui, Xu Qiao, Yao Shi
    更新日期:2017-11-19
  • Supercritical Methane Sorption on Organic-Rich Shales over a Wide Temperature Range
    Energy Fuels (IF 3.091) Pub Date : 2017-11-17
    Feng Yang, Congjiao Xie, Shang Xu, Zhengfu Ning, Bernhard M. Krooss

    Methane sorption on organic-rich shales over wide temperature and pressure ranges (30–120 °C, up to 25 MPa) is analyzed by the pore filling/potential theory. The supercritical Dubinin–Astakhov (SDA) sorption model using a density term instead of the pseudosaturation vapor term is extended to methane sorption isotherms of shales with high accuracy. A modified adsorption potential approach is suggested to analyze the temperature dependence of supercritical methane sorption on shales. The temperature-invariant characteristic curves are obtained using the modified adsorption potential approach. A characteristic curve equation derived from the SDA model is provided to predict sorption isotherms at other temperatures using one isotherm. The physical meaning of the characteristic curve has been discussed, and it comprehensively reflects the available pore space for methane sorption and the affinity between methane molecules and organic matter. According to methane characteristic curves of shales and clay minerals, shales in the gas window show higher affinity than shales in the oil window and clay minerals, though the clay minerals may provide comparable adsorbed volume. The adsorption characteristic energy shows a parabola-like shape with a minimum of approximately Req = 1.1%, which is related to the evolution of the porosity of the shales. This study advanced the fundamental understanding of the dynamic process of methane sorption on shales.

    更新日期:2017-11-19
  • New Two-Dimensional Particle-Scale Model To Simulate Asphaltene Deposition in Wellbores and Pipelines
    Energy Fuels (IF 3.091) Pub Date : 2017-11-17
    Aliakbar Hassanpouryouzband, Edris Joonaki, Vahid Taghikhani, Ramin Bozorgmehry Boozarjomehry, Antonin Chapoy, Bahman Tohidi

    A new two-dimensional dynamic model was developed to simulate asphaltene precipitation, aggregation, and deposition at isothermal and non-isothermal conditions. The perturbed-chain statistical associating fluid theory equation of state was used to model the asphaltene precipitation. Also, novel kinetic models were used to account for the aggregation and deposition of asphaltene particles. The effect of the aggregate size on the rate of aggregation and deposition was studied, and it was concluded that the rate of asphaltene deposition increases, while the concentration of nanoaggregates increases in the well column. The tendency of smaller aggregates to deposit on the surface could be explained as a result of the increase in the diffusion coefficient of asphaltene aggregates. The results obtained from the new model for the rate and amount of asphaltene deposition were compared to the experimental data reported in the literature. It was shown that the results of the new simulation were in good agreement with the experimental data.

    更新日期:2017-11-19
  • Polymer Gel Systems for Water Management in High-Temperature Petroleum Reservoirs: A Chemical Review
    Energy Fuels (IF 3.091) Pub Date : 2017-11-17
    Daoyi Zhu, Baojun Bai, Jirui Hou

    Polymer gel systems as water management materials have been widely used in recent years for enhanced oil recovery applications. However, most polymer gel systems are limited in their ability to withstand the harsh environments of high temperature and high salinity. Those polymer gel systems that can handle high-temperature excessive water treatments are reviewed in this paper and categorized into three major types: in situ cross-linked polymer gels, preformed gels, and foamed gels. Future directions for the development of polymer gel systems for high-temperature conditions are recommended. For excessive water management with temperatures from 80 to 120 °C, current polymer systems are substantially adequate. Polymer gel systems composed of partially hydrolyzed polyacrylamide (HPAM)/chromium can be combined with nanoparticle technology to elongate their gelation time and reduce the adsorption of chromium ions in the formation. Phenolic resin cross-linker systems have reasonable gelation times and gel strengths; however, more environmentally friendly cross-linkers should be developed to meet the increasingly stringent environmental requirements. For particle gels, the addition of functional monomer(s) can improve the antitemperature performance. When the applied temperatures reach 120 °C, inorganic cross-linker systems are no longer applicable, and the gelation time of organic cross-linking polymer gel systems and gel thermal stability will decrease significantly due to fast cross-linking reactions. During this period, retarders can be used to elongate the gelation time, and gel strength enhancers (e.g., cement, silica) can also be applied to improve the gel strength at such extremely high temperatures. Most importantly, novel polymers (e.g., ter- or tetrapolymers), functional monomers, and environmentally friendly cross-linkers need to be discovered and developed for polymer gel applications. Second cross-linking systems can be applied to further enhance the strength of the particle gels in harsh conditions. On the basis of these developments, foamed gels can be well-implemented in fractures and wormholes to save the amount of injected gels.

    更新日期:2017-11-19
  • Metals and Other Elements in Biocrude from Fast and Isothermal Hydrothermal Liquefaction of Microalgae
    Energy Fuels (IF 3.091) Pub Date : 2017-11-17
    Jimeng Jiang, Phillip. E. Savage

    We determined the effects of different hydrothermal liquefaction (HTL) process variables (temperature, holding time, algae loading, and water loading) on 13 different elements in biocrude and the aqueous phase co-product. Reaction conditions included both fast and isothermal HTL. The concentrations of P, Mg, Na, and Ca in the biocrude had their highest values at the mildest HTL conditions explored, and the concentrations decreased precipitously as even moderate HTL conditions were used. The concentrations of Zn, Cu, and Ni do not show much variation with HTL severity, whereas the concentration of Fe in the biocrude first increases and then decreases. P and Na were the most abundant elements in the biocrude from fast HTL, but Fe was the most abundant from isothermal HTL. These results show that the HTL conditions can influence the concentrations of different metals and inorganic species in algal biocrude from HTL.

    更新日期:2017-11-19
  • Study on the influencing factors of the distribution characteristics of polycyclic aromatic hydrocarbons in condensable particulate matter
    Energy Fuels (IF 3.091) Pub Date : 2017-11-17
    Jingwei Li, Xiaodong Li, Chenyang Zhou, Min Li, Shengyong Lu, Jianhua Yan, Zhifu Qi

    Condensable particulate matter (PM) contributes significantly to the total emissions of particulate matter from stationary sources. The distribution characteristics of polycyclic aromatic hydrocarbons (PAHs) in condensable PM from a coal-fired power plant were investigated. The influence of the sulfur content of the burning coal and the wet electrostatic precipitator (WESP) on the PAH distributions in condensable PM was analyzed. The total mass concentrations of PAHs in condensable PM were quite low (1.05 µg/m³ in Stage 1, 0.69 µg/m³ in Stage 2, and 1.89 µg/m³ in Stage 3). 3-ring and 4-ring PAHs were the major PAH compounds in condensable PM. The higher sulfur conten in the burning coal led to greater PAH contents and emissions in condensable PM than the lower sulfur content. The sulfur content could promote the formation of PAHs during the coal combustion process. The WESP had good removal efficiency (approximately 63%) of total PAH emissions in condensable PM. The WESP could obviously decrease the total toxic equivalent (TEQ) values of PAHs in condensable PM. The total TEQs of PAHs in condensable PM were mostly contributed by the 3-ring and 5-ring PAHs in this study.

    更新日期:2017-11-19
  • Small skeletal kinetic reaction mechanism for ethylene-air combustion
    Energy Fuels (IF 3.091) Pub Date : 2017-11-17
    Niklas Zettervall, Christer Fureby, Elna Johanna Kristina Nilsson

    Ethylene is a fuel considered for high speed ram- and scramjet combustion applications, mainly because of the short ignition delay time resulting from its high reactivity. Further research and development on these combustion systems would benefit from simulations of Large Eddy (LES) type, which allow some chemical detail to accurately predict combustion characteristics and pollutant formation. In the present work a chemical kinetic mechanism suitable for LES is presented, consisting of 66 irreversible reactions between 232 species. The mechanism is extensively validated for combustion characteristics related to ignition and flame propagation, over a wide range of pressure, temperature and equivalence ratios that previously published mechanism of this size have not covered. Agreement with a detailed reference mechanism is good for ignition delay, flame temperature and laminar burning velocities. In addition, overall concentration profiles of major stable products are in overall good agreement with reference mechanism. The skeletal mechanism shows an overall good performance in combination with a numerical stability and short computation time, making it highly suitable for combustion Large Eddy Simulation (LES).

    更新日期:2017-11-19
  • Efficiency of carbon dioxide storage and enhanced methane recovery in a high rank coal
    Energy Fuels (IF 3.091) Pub Date : 2017-11-17
    Mojgan Hadi Mosleh, Majid Sedighi, Philip J. Vardon, Matthew Turner

    High affinity and adsorption capacity of coal to carbon dioxide provides alternative approach for the enhanced recovery of methane from unminable coalfields (CO2-ECBM) by which a potential solution for long-term CO2 sequestration in deep geological formations can also be achieved. However, due to chemo-mechanical effects induced by the interactions between CO2 and coal, the effective methane production and carbon dioxide storage can be degraded which has caused uncertainties about the techno-economic feasibility of the CO2-ECBM process. This study presents an experimental investigation that aims to address key knowledge gaps related to the efficiency of CO2 storage and CH4 recovery in high rank coals for which comprehensive experimental data set and analysis are largely missing. Competitive displacements of CH4 with N2 or CO2 in an anthracite coal sample from South Wales coalfield have been studies, based on a series of core flooding experiments. The results show that the N2 breakthrough time (the time at which 1% of the total gas injected was recovered) was almost spontaneous whereas a considerably delayed breakthrough time was observed for the case of CO2-ECBM experiment. In addition it was observed that for the CO2-ECBM experiment, the ratios of CH4 recovery with respect to the total amount of gas injected and gas stored were higher by factors of 10 and 2.4, respectively. The results also show that 90% of the total N2 injected was produced in the outflow gas, whereas for the case of the CO2 experiment, only 63% of the total injected CO2 was produced. Presence of high amount of N2 in the outflow may lead to additional challenges in order to separate N2 from CH4 and thus affects the efficiency of the N2-ECBM method. Under the conditions of the experiments, the total CH4 displacement ratio and breakthrough for the case CO2-ECBM were found to be more favorable compared to those obtained from N2-ECBM. This study provides new insights into the efficiency of CO2-ECBM process and offers a comprehensive experimental data set that can be used for testing the accuracy of predictive models.

    更新日期:2017-11-19
  • Effects of Bias Concentration Ratio on Ignition Characteristics of Parallel Bias Pulverized-Coal Jets
    Energy Fuels (IF 3.091) Pub Date : 2017-11-17
    Guang Zeng, Shaozeng Sun, Wenda Zhang, Zhiqiang Zhao, Yijun Zhao

    To further advance pulverized coal (PC) combustion theory and enable the rational development of horizontal bias combustion technology, combustion experiments were conducted in a 250-kW pilot-scale bias combustion simulator; multiple research means of combustion temperatures, flame spectra, burnout rates of residual solids and NOx formation were used. A blend of sub-bituminous coal from Indonesia and bituminous coal from Australia was tested. The effects of bias concentration ratio (BCR) on the ignition characteristics of parallel bias PC jets in a reducing atmosphere were investigated. The results indicate that with increasing BCR for parallel bias PC jets, the standoff distance gradually decreased, the peaks of subsequent combustion temperature and visible-light intensity gradually increased, the continuous flame regions became advanced and concentrated, the flame stability gradually increased, the burnout rate gradually increased, the NOx formation gradually decreased, and the ignition characteristics gradually improved. Except at a BCR of 1, the PC ignition of fuel-rich jet was better than that of the fuel-lean jet, and the continuous flame region of parallel bias PC jets leant obviously in the direction of the fuel-rich jet. The bias combustion changed the ignition mode of primary air PC jets; there was homogeneous ignition mode at a BCR of 1; when BCR increased to no less than 3, the ignition mode changed to homogeneous–heterogeneous combined ignition, which is beneficial to the PC ignition conditions. Based on the research results in this paper, the recommended BCR for the design of horizontal bias combustion PC burner was 4~5.

    更新日期:2017-11-19
  • Optimization of parameters on the generation of hydrogen in combined slow pyrolysis and steam gasification of biomass
    Energy Fuels (IF 3.091) Pub Date : 2017-11-17
    Prakash Parthasarathy, Sheeba Narayanan, Selim Ceylan, Nugroho Agung Pambudi

    This study investigates the effect of controlling parameters of slow pyrolysis and steam gasification on the generation of hydrogen. Some native biomass wastes were first slow pyrolyzed and generated chars were then steam gasified to generate hydrogen. In slow pyrolysis, parameters such as temperature, residence time and particle size were optimized. Whilst in steam gasification, the variables such as temperature, residence time, steam to biomass ratio (S/B), catalysts, catalysts composition, sorbents, sorbents composition and effective catalyst-sorbent composition were optimized. It was found that the highest gasification temperature (800 °C) yielded the maximum hydrogen. Further, an optimal residence time of 30 min was found to generate maximum hydrogen. It was observed that optimum S/B for hydrogen generation was different for different biomass. Amongst the selected catalysts, KCl generated the maximum hydrogen composition. Of the selected sorbents, CaO generated the maximum hydrogen composition. The combined effect of KCl-CaO generated the maximum hydrogen generation.

    更新日期:2017-11-19
  • Demineralization study of high ash Permian coal with Pseudomonas mendocina strain B6-1: A case study of South Karanpura coalfield, Jharkhand, India
    Energy Fuels (IF 3.091) Pub Date : 2017-11-17
    Aniruddha Kumar, Alok Kumar Singh, Prakash Kumar Singh, Asha Lata Singh, Mrityunjay Kumar Jha

    This paper entails the results of demineralization carried out on the Karanpura Gondwana coals having high ash (30.57%-21.80%) and low sulfur (0.29%-0.20%) content. The coal samples were subjected to demineralization using Pseudomonas mendocina strain B6-1 and the effect of various parameters like pH, temperature, incubation time and pulp density was observed. Optimum values of demineralization were found at pH 6.0, temperature 35°C, 6.0% (w/v) of pulp density and incubation time of 7 days respectively. Reduction in the Mineral matter (mean 13.72%–29.10%) content led to a relative increase in vitrinite, Inertinite and liptinite macerals. Further, the treatment has also caused an increase in the useful heat value, gross calorific value and net calorific value of coal, from (mean values) 4824.86 cal/g to 5192.06 cal/g; 5396.72 cal/g to 5647.47 cal/g; 5059.30 cal/g to 5273.80 cal/g respectively. The method is eco-friendly and is useful in obtaining clean fuel.

    更新日期:2017-11-19
  • Comparison of Experimental Techniques at Ambient and High Pressure Conditions for Evaluation of Chemistries against Asphaltene Aggregation and Deposition: New Application of HPHT-QCM
    Energy Fuels (IF 3.091) Pub Date : 2017-11-17
    Edris Joonaki, Rod Burgass, Aliakbar Hassanpouryouzband, Bahman Tohidi

    Asphaltene precipitation and deposition caused by temperature variation, pressure depletion and oil composition changes can result in formation damage, oil production reduction and increased operating costs. Use of chemical additives is probably the most effective option for preventing or reducing asphaltene problems. Selection of inhibitors for asphaltene deposition is commonly based upon simple tests conducted on stabilised crude oil samples at ambient conditions. The results obtained from the current testing techniques in the labs are sometimes in disagreement with the outcome at field conditions. Therefore, the current techniques which are employed to select the most appropriate asphaltene inhibitor based on their efficiency should be revisited to provide a better methodology for choosing the most suitable strategy for inhibitor/solvent injection. This research study addresses this asphaltene challenge using a Quartz Crystal Microbalance (QCM) based technique, with emphasis on selection of chemical additives for remediation/prevention strategies to handle gas induced asphaltene deposition problems. The proposed technique can work at high pressure conditions, simulating the effect of pressure and dissolved gas on asphaltene phase behaviour and deposition tendencies with and without inhibitors. It can also assess the deposition rate onto the quartz crystal surface due to asphaltene deposition under real reservoir conditions. In this study, the ability of different asphaltene inhibitors to shift asphaltene onset points (AOPs) and reduce the amount of deposited asphaltenes in dead crude oils is investigated. A comparison between the results of the QCM technique at high pressure-high temperature and dead crude oil testing at ambient condition is presented. The results of this work indicate that the change in temperature, pressure and presence of gas could alter the ranking of chemistries for mitigating asphaltene challenges.

    更新日期:2017-11-19
  • Experimental Study on the Effect of Thermo-responsive Secundine Inhibitor on Coal Spontaneous Combustion
    Energy Fuels (IF 3.091) Pub Date : 2017-11-17
    Chuanbo Cui, Shuguang Jiang, Weiqing Zhang

    When high water-cut physical inhibitor (HWPI) is sprayed on the coal in goaf, moisture in coal will undergo a substantial reduction under the influence of liquid flow and water evaporation, which severely weakens the inhibitory effect of HWPI and greatly shortens its inhibitory lifetime. Therefore, this paper proposes a thermo-responsive secundine inhibitor (TSI) to solve the problem of poor water retention and short inhibitory lifetime by sealing HWPI in the thermo-responsive secundine (TS). Before the ambient temperature (30 °C) reaches the trigger temperature, the water retention rate of TSI is 100%. After the trigger temperature is reached, TSI will quickly release a large amount of HWPI to suppress coal spontaneous combustion. The releasing time and trigger temperature of TSI drop rapidly with the increase of borehole diameter and borehole number, while its weight loss grows with the increase of borehole diameter and borehole number. The experimental results reveal that the borehole diameter of 2.5 mm and the borehole number of 12 are the optimal conditions for TSI to release more HWPI in a relatively short period of time.

    更新日期:2017-11-19
  • Performance, combustion and emission analysis of neat palm oil bio-diesel and higher alcohol blends in diesel engine
    Energy Fuels (IF 3.091) Pub Date : 2017-11-17
    Yuvarajan Devarajan, Dinesh Babu Munuswamy, Arulprakasajothi Mahalingam, Beemkumar Nagappan

    In this work, palm oil biodiesel (POBD100) with cyclo-octanol additive was employed in a constant speed diesel engine and its effects on engine combustion, emission and performance were studied. The biodiesel produced from palm oil by conventional transesterification process, sodium hydroxide and methanol were involved in the conversion of oil into biodiesel. The five fuels evaluated were neat palm oil biodiesel (POBD100), octanol blended with palm oil biodiesel by10% volume (POBD90O10), octanol blended with palm oil biodiesel by20% volume (POBD80O20), octanol blended with palm oil biodiesel by30% volume (POBD70O30) and petroleum diesel. The experimental results revealed that with the increased octanol fraction, the combustion was smooth. All the octanol and biodiesel blends provide earlier combustion when compared to neat palm oil biodiesel which leads to higher thermal efficiency, lower fuel consumption, lower peak pressure, and shorter ignition delay. All the emissions are reduced by the addition of cyclo-octanol in palm oil biodiesel in all loads owing to the higher oxygen concentration of air/fuel mixtures and improved atomization. Based on the outcome of this study palm oil biodiesel and cyclo-octanol blends can be employed as a potential alternative fuel for existing unmodified diesel engines owing to its improved combustion, emission and performance characteristics.

    更新日期:2017-11-19
  • Particle size distributions of fly ash arising from vaporized components of coal combustion - a comparison of theory and experiment
    Energy Fuels (IF 3.091) Pub Date : 2017-11-17
    Huimin Liu, Yueming Wang, Jost O.L. Wendt

    A 100kW rated down-fired pilot scale combustor was used to explore sub-micron coal ash aerosol formation for two coals under various air and oxy-combustion atmospheres. Particle size distribution (PSD) data were obtained through isokinetic sampling and then by electron mobility and light scattering particle sizing. The submicron portion of the PSD exhibited an “accumulation” mode at ~0.27µm and in some cases an additional “nucleation” mode between 0.03µm and 0.07µm. Predictions of the temporal evolution of the sub-micron aerosol were made using a sectional coagulation model. Comparison with experimental measurements suggested that the “accumulation” mode was formed by coagulation of vaporized silicon rich species which occurred, and was completed, very close to the parent char particle, not in the mixed flue gas. This showed the importance of carefully characterizing microscale mixing phenomena around individual particles. For the sodium rich species that had heretofore been thought to nucleate in the sampling probe, it now seems that they nucleate within the furnace, but coagulation without particle growth was insufficient to explain the location of the “nucleation” modes for all but one case explored. For that one coal the “nucleation” mode was dominated by high concentrations of particles containing calcium, and there its location was consistent with coagulation. Additional modeling involving both coagulation and particle growth is required.

    更新日期:2017-11-19
  • Alcohol Stabilization of Low Water Content Pyrolysis Oil during High Temperature Treatment
    Energy Fuels (IF 3.091) Pub Date : 2017-11-16
    Laibao Zhang, Yan Luo, Rangana Wijayapala, Keisha B. Walters

    The addition of alcohols is a promising method to pretreat and stabilize pyrolysis oil by converting carboxylic acids and reactive carbonyl compounds into esters, ethers, and acetals. In this study a series of alcohols—methanol, ethanol, 1-propanol, 2-propanol, or 1-octanol—was added to crude pyrolysis oil, and these mixtures were stored at 200 °C for different periods from 6 to 50 h to investigate the impact of heat treatment on the oils’ physicochemical properties. All oil/alcohol mixtures were characterized by Karl Fisher titration, viscometer/rheometer, differential scanning calorimetry (DSC), gel permeation chromatography (GPC), Fourier transform infrared (FTIR) spectroscopy, and gas chromatography–mass (GC-MS) spectrometry. Phase separation is observed for all aged oil/alcohol mixtures. The time-dependent rheologies of heat treated oil/1-propanol, oil/2-propanol, and oil/1-octanol mixtures are found to be well fitted by the Herschel–Bulkley model. Isothermal DSC traces directly confirm that low molecular mass (LMM) alcohols (methanol, ethanol, 1-propanol, and 2-propanol) improve the stability of pyrolysis oil. Although 1-octanol is less efficient in slowing the aging reactions, it significantly reduces the increase rate of viscosity and molecular weight of pyrolysis oil compared with LMM alcohols. FTIR spectra suggest reactive carbonyl and aldehyde groups are captured by the added monofunctional alcohols. GC-MS results indicate esterifications contribute significantly to mitigate aging reactions. The introduction of LMM alcohols or a combination of LMM alcohols and HMM alcohols is a promising pretreatment method before the further catalytic upgrading procedure on the crude pyrolysis oil.

    更新日期:2017-11-17
  • Numerical Simulation and Experimental Research on Drying Behavior of a Single Lignite Particle (SLP) under High-Temperature Flue Gas
    Energy Fuels (IF 3.091) Pub Date : 2017-11-16
    Hao Li, Shouyu Zhang, You Li, Chen Mu, Yifan Zhang, Fenghao Jiang, Caiwei Wang

    The drying behavior of a single lignite particle (SLP) in high-temperature (600–900 °C) flue gas was investigated by experiment and numerical calculations. A self-designed horizontal fixed-bed reactor was employed for high-temperature drying experiments. Based on the drying curves obtained from these experiments, no constant-drying-rate stage was found, and the SLP drying process included stages with increasing and decreasing drying rates. To explore the drying process in depth, a mathematical model was developed in which the SLP was simplified into a simple spherical model. Based on the dry–wet zone theory, the heat- and mass-transfer equations were established to describe the drying process. The simulated results calculated using MATLAB agreed well with the experimental data. The model can predict SLP drying behaviors including the effects of the drying time, the surface and internal temperature distributions of the lignite particle, the migration of the evaporation interface inside the particle, and so on. The predicted results indicated that the migration velocity of the evaporation interface and the temperature were linearly dependent and that a temperature of 700 °C was the most suitable temperature for lignite drying. Furthermore, the drying time can be predicted using the model according to practical applications. Thus, the model can be used for the optimization of the drying process parameters and can offer guidance for the development of new drying technologies.

    更新日期:2017-11-17
  • Characterization of the Solid Residue and the Liquid Extract Separated by Propane-Induced Crude Oil Fractionation
    Energy Fuels (IF 3.091) Pub Date : 2017-11-16
    Marcia Cristina Khalil de Oliveira, Humberto Lopes, CARMEN DA SILVA TEIXEIRA, Luiz Silvino Chinelatto Júnior, GASPAR GONZALEZ, RODRIGO ALTOE

    Following a previously reported experimental procedure, a heavy petroleum sample was fractionated by mixing a predefined volume of oil with liquid propane above its saturation pressure at different propane/oil ratios. The separated fractions, considered two mutually saturated liquid phases in equilibrium at p and T separation conditions, were denominated solid residue and liquid extract and were characterized by chemical and spectroscopic methods including elemental compositional and SARA analyses, FTIR and NMR. The results show that the amount yielded or produced increases for the solid residue and decreases for the liquid extract as the propane/oil ratio increases and that the four SARA components are present in both fractions, independently of the propane/oil ratio used in the fractionation process. The data also indicate that polar components are present in the liquid extract even at the highest dilutions that correspond to rather low solubility parameters. Complementary results show that after the flocculation process and the subsequent liberation of propane the solid residue and the liquid extract were easily recombined with minimal losses by remixing both fractions. Physical and chemical analysis indicated that the recombined and the original oil presented similar characteristics in terms of API gravity, SARA, elemental composition, FTIR and NMR but substantial differences in their rheological behavior. The similarity between original and recombined oil is also evidenced by 1H DOSY-NMR that shows that sets of aggregates are present in the spectra for both oil samples.

    更新日期:2017-11-17
  • Enhanced Adsorption Performance of Aromatics on a Novel Chromium-Based MIL-101@graphite oxide Composite
    Energy Fuels (IF 3.091) Pub Date : 2017-11-16
    Xuejiao Sun, Daofei Lv, Yongwei Chen, Ying Wu, Qi-Hui Wu, Qibin Xia, Zhong Li

    Chromium-based MIL-101 and graphite oxide (GO) composite (MIL-101@GO) was synthesized and applied for adsorption performances towards a series of aromatics (benzene, toluene and ethylbenzene). Desorption activation energies of aromatics on this composite were evaluated based on temperature programmed desorption (TPD) experiments. The results indicated that the aromatic uptakes on the composite increase with the carbon number at low pressure. In contrast, at high pressure, their adsorption capacities exhibit an opposite trend. The composite possesses high uptakes of the aromatics, which are approximately 1.8-6.0 times higher comparing with conventional adsorbents. The desorption activation energies of the aromatics increase with the carbon number of aromatics. Additionally, the adsorption of ethylbenzene on the composite is highly reversible. More importantly, the MIL-101@GO composite exhibits enhanced thermal conductivity up to 0.369 W/mK at 303 K. MIL-101@GO composite with high adsorption capacity, enhanced thermal conductivity and efficient recyclability provided a promising candidate for practical applications in field of volatile organic compounds adsorption.

    更新日期:2017-11-17
  • Role of Vanadylporphyrins in the Flocculation and Sedimentation of Asphaltenes of Heavy Oils with High Vanadium Content
    Energy Fuels (IF 3.091) Pub Date : 2017-11-16
    Yulia Yurevna Borisova, Elvira Gabidullovna Tazeeva, Nikolay Alexandrovich Mironov, Dmitry Nikolaevich Borisov, Svetlana Gabidullinovna Yakubova, Guzalia Rashidovna Abilova, Kirill Olegovich Sinyashin, Makhmut Renatovich Yakubov

    Extraction by N,N-dimethylformamide with further column chromatography allowed obtaining concentrate of vanadylporphyrins from asphaltenes of heavy sulfurous oils with high vanadium content. The prevailing types of vanadylporphyrins, their ratio, and molecular mass distribution were determined. The influence of obtained vanadylporphyrin concentrates on the stability of asphaltenes in the system “solvent/precipitator” was investigated. Kinetic studies using UV–vis spectroscopy have revealed that an increase in the content of vanadylporphyrins in asphaltenes leads to acceleration of their deposition from solution and destabilization of colloidal systems.

    更新日期:2017-11-16
  • Insight into the pore structure of tight gas sandstones: A case study in the Ordos Basin, NW China
    Energy Fuels (IF 3.091) Pub Date : 2017-11-16
    Hao Wu, Youliang Ji, Ruie Liu, Chunlin Zhang, Sheng Chen

    A wide spectrum of pore size distributions (PSD) exists in tight gas sandstones, ranging from several nanometers to several hundred micrometers in radius, which controls both the physical rock-flow capacity and storage capacity. Thin-section, scanning electron microscope (SEM), field emission scanning electron microscope (FE-SEM), high-pressure mercury intrusion (HPMI), constant-rate mercury intrusion (CRMI) and micro-CT scanning experiments are performed on tight sandstone samples from the eighth member of the Middle Permian Shihezi Formation (P2h8) in the Ordos Basin to better understand the pore-system characteristics of a tight gas sandstone. The results of this case study show that various types of pores exist in the P2h8 sandstones: residual intergranular pores, intraparticle dissolution pores, intercrystalline pores, and small micro-cracks are observed. We combine HPMI and CRMI to determine the PSD; the pore sizes range from 3.7 nm to 600 μm in radius. The multimodal PSD is characterized by two broad peaks. The right peak with radii between 50 and 600 μm acts as a pore body and is associated with residual intergranular pores and partial-dissolution pores in grains. The left peak, which corresponds to the throat, shows notable fluctuations and ranges from 3.7 nm to 50 μm; the pores within this size range are mostly associated with dissolution pores and intercrystalline pores. The permeability is mainly controlled by relatively large throats with a lower percentage. When the permeability is less than 1.0 mD, it is dominated by nanopores and micropores; in contrast, higher permeability is almost solely dominated by micropores. Additionally, nanopores are increasingly important in reservoir storage capabilities with decreasing permeability. A new empirical equation to estimate the permeability indicates that the pore throat radius of r30, which is the optimal representative for the permeability estimation of tight gas sandstones, generates the strongest correlation with the porosity and permeability.

    更新日期:2017-11-16
  • Development of In-Situ CO2 Generation Formulations for Enhanced Oil Recovery
    Energy Fuels (IF 3.091) Pub Date : 2017-11-16
    Shuoshi Wang, Mohannad J. Kadhum, Changlong Chen, Benjamin Shiau, Jeffrey H. Harwell

    Carbon dioxide flooding of oil reservoirs represents one of the most proven tertiary oil recovery practices. However, there are significant challenges associated with applying CO2 flooding in certain onshore or offshore fields and applications. The common challenges include: limited supply of CO2, transportation, capital cost investment, and corrosion. For offshore flooding, the critical challenge could be more related to extreme remote and significant project cost increase. In this work, we investigated delivering CO2 indirectly to the subsurface formation by injecting the concentrated solution of ammonium carbamate (AC) as CO2 generated species. Ammonium carbamate, a highly water soluble solid (40 wt. %) and commercially available, can be dissolved and injected to the reservoir where it decomposes at reservoir condition releasing products of CO2 and ammonia. The produced CO2 results in lowering oil viscosity and oil swelling. Increase of ammonia concentration results in sand wettability reversal due to elevated alkalinity. Tertiary oil recovery performance of ammonium carbamate solution was evaluated by conducting multiple sand packs and one core flooding test at various pressure and temperature conditions. Dodecane and several dead crude oils were used as oil phase. Injected AC concentrations tested were ranging from 5 to 35 wt. %, operational pressure, P ranging from atmospheric to 4000 psi, and the pre-set temperature ranging from 96 to 133℃. Tests were conducted by injecting the selected oil phase into the porous media followed by a standard water (brine) flooding, a total of 2 pore volumes (PV) of AC injection followed by a second water flooding. The average tertiary recovery observed from all the tests was found to be 29%. Results of laboratory experiments clearly demonstrated the potentials of this new formulation for tertiary oil recovery. Mainly it requires minimal capital investment upfront in comparison to CO2 flooding and largely eliminates the occurrence of gravity segregation and reduces adverse fingering behaviors. The results of this work serve as a successful proof of concept study for their potential applications of tertiary oil recovery for both onshore and offshore fields.

    更新日期:2017-11-16
  • Experimental Study on the Turbulent Premixed Flame Structural Characteristics Based on the Wavelet Transform
    Energy Fuels (IF 3.091) Pub Date : 2017-11-15
    Yan-Huan Jiang, Guo-Xiu Li, Hong-Meng Li, Lei Li, Fu-Sheng Li

    To investigate the effect of the flame inherent instabilities and turbulence on the flame structural characteristics, premixed combustion experiments of 50% H2/50% CO at a equivalence ratio of 0.6 were conducted in a turbulent combustion bomb in atmospheric temperature and pressure. The correlation degree was defined to study the correlation relation between flame structural characteristics at different moments, and the wavelet transform was used to investigate the detail components at different scales. The results indicate that, with the development of the flame, the cellular structure was enhanced and the correlation degree gradually decreased. The fluctuations of the detail components at the larger scale were stronger and included more energy, which corresponded to the main factor causing the flame front complex. With the turbulence intensity increase, the root mean square amplitude and energy of the detail components increased, leading to the increase of the interaction of different disturbances, while the correlation degree of the flame decreased. The correlation degree of the detail components presented a staggered distribution of higher and lower values, which indicated the complex changes of the disturbances at different scales.

    更新日期:2017-11-16
  • Experimental and Numerical Investigation of the Laminar Burning Velocity and Combustion Characteristics of Biogas at High Pressures
    Energy Fuels (IF 3.091) Pub Date : 2017-11-15
    Mohammad Hossein Askari, Mehdi Ashjaee, Sadrollah Karaminejad

    Continuous variation in the composition of gaseous fuels derived from biomass is a challenge in designing efficient combustors for using them. In this study, experimental measurement of the laminar burning velocity (ul) of three different compositions of biogas fuel containing equimolar H2/CO mixtures and N2 ranging from 40 to 60% by volume is conducted. Numerical calculations of the flame structure, adiabatic flame temperature (Tad), species concentrations, and sensitivity analysis are also performed. Investigations are conducted over a practical range of equivalence ratios (ranging from 0.4 to 1.2) and at high pressures up to 4 bar. The experimental method of schlieren in a high-pressure combustion chamber is used for flame speed measurement. Numerical calculations are performed using the premixed code of CHEMKIN using four well-known reaction mechanisms. Laminar burning velocities calculated using the USC Mech Version II mechanism showed the best agreement with the experiments. The results indicated that the mole fraction of the H radical increases by equivalence ratio at the whole range considered in this study, while the OH radical declares its maximum concentration at stoichiometric conditions. This causes the maximum value of ul to occur at the equivalence ratio of 1.2. Tad increases by increasing pressure, especially near stoichiometric conditions and for lower N2-containing fuels. The equivalence ratio of the maximum flame temperature changes from the rich state (at φ = 1.05) to the stoichiometric state by increasing the N2 content of fuel from 40 to 60%. H2 plays a dominant role in the combustion of biogas fuel at high H2 concentration conditions. More than 50% of hydrogen burns before the flame front, while CO mainly burns after this position.

    更新日期:2017-11-16
  • Three-Dimensional Full Loop Modeling and Optimization of an in Situ Gasification Chemical Looping Combustion System
    Energy Fuels (IF 3.091) Pub Date : 2017-11-15
    Yali Shao, Yong Zhang, Xiaojia Wang, Xudong Wang, Baosheng Jin, Hao Liu
    更新日期:2017-11-16
  • Formation of Nitrogen-Containing Organic Aerosol during Combustion of High-Sulfur-Content Coal
    Energy Fuels (IF 3.091) Pub Date : 2017-11-15
    Xiaofei Wang, Hanliu Wang, He Jing, Wei-Ning Wang, Weidong Cui, Brent J. Williams, Pratim Biswas
    更新日期:2017-11-16
  • Energy assessment of wood pyrolysis coproducts for drying and power generation
    Energy Fuels (IF 3.091) Pub Date : 2017-11-15
    Emanuele Pereira, Marcio Martins, Luis Felipe dos Santos, Angélica de Cassia Carneiro

    Carbonization is the process in which the wood is heated in a closed environment with controlled amount of air, producing charcoal as a solid product of the process and secreting water vapor, organic liquids and non-condensable gases. The burning of these gases generates energy that can be used for the drying wood to be carbonized or for the generation of electric power in the carbonization plant itself. The present study had the purpose to conduct an energetic survey of the fractions from the charcoal production process, aiming to subsidize and to encourage the technological development of equipment for the energetic use of the carbonization gases. The results showed that the energy contained in non-condensed gases and in pyroligneous liquid corresponds to a total of 31% of the wood energy used. Two scenarios of synchronism of four kilns were studied in pyrolysis and a maximum and constant potential of 9.7 MW was obtained in scenario 2. The burner was efficient in the emission control, the CO and CH4 reductions were in the range of 97-99% and 68-91% respectively. Thus, the burner is a promising technology for the reduction of greenhouse gases and for the generation of thermal energy from carbonization co-products.

    更新日期:2017-11-16
  • FIRST STUDY OF POLY(3-METHYLENE-2-PYRROLIDONE) AS A KINETIC HYDRATE INHIBITOR
    Energy Fuels (IF 3.091) Pub Date : 2017-11-15
    Eirin Abrahamsen, Ingrid Marie Heyns, Nicolas von Solms, Rueben Pfukwa, Bert Klumperman, Malcolm A. Kelland

    Formation of gas hydrates is a problem in the petroleum industry where the gas hydrates can cause blockage of the flowlines. Kinetic hydrate inhibitors (KHIs) are water-soluble polymers, sometimes used in combination synergistically or with non-polymeric synergists, that are used to prevent gas hydrate blockages. They have been used in the field successfully since 1995. In this paper, we present the first KHI results for the polymer, poly(3-methylene-2-pyrrolidone) (P(3M2P)), which is structurally similar to poly(N-vinylpyrrolidone) (PVP), one of the first KHIs to be discovered. 3M2P polymers with different molecular weights (5500 and 2500 g/mole) and at different concentrations (2500, 5000 and 7500 ppm) were investigated for their KHI performance on SII hydrates in high-pressure rocking cells. We also investigated the synergistic effect of P(3M2P) with n-butyl glycol ether (BGE), a known synergist for some KHI polymers. At the lower concentrations, P(3M2P) gives a similar performance to PVP (Mw = 8000-9000 g/mole). However, PVP outperforms both samples of P(3M2P) at 7500 ppm, with and without BGE. We suggest that the reasons for the performance level of P(3M2P) are related to greater resonance stabilization of the amide group in P(3M2P) compared to PVP. Also, the pyrrolidone ring of the PVP repeat unit has a larger hydrophobic sequence of three methylene units compared to the two methylene units in the pyrrolidone ring of P(3M2P). This relates well to previous studies where larger hydrophobic groups are preferable in KHI polymers as long as they are water-soluble at hydrate-forming temperatures.

    更新日期:2017-11-16
  • Characteristic Properties of Lignite to be Converted to High-Strength Coke by Hot-Briquetting and Carbonization
    Energy Fuels (IF 3.091) Pub Date : 2017-11-15
    Shinji Kudo, Aska Mori, Gentaro Hayashi, Takuya Yoshida, Noriyuki Okuyama, Koyo Norinaga, Jun-ichiro Hayashi

    A sequence of hot-briquetting and carbonization (HBC) is a promising technology for the production of coke with a high mechanical strength from lignite, but factors affecting the coke strength have not yet been fully understood. The HBC cokes prepared from twelve lignites in this study showed diverse tensile strength (e.g., from 0.2 to 31.2 MPa in the preparation at 200 °C and 112 MPa for hot-briquetting and 1000 °C for carbonization), and the coke strengths could not be explained by differences in commonly used structural properties of the parent lignites, such as elemental composition and contents of volatile matter/fixed carbon and ash. In this study, two methods were proposed for correlating the coke strength with the lignite properties, which employed the chemical structure analyzed by solid-state 13C NMR or the volumetric shrinkage during carbonization. A stronger coke was obtained from lignite that contained more aliphatic carbons (less aromatic carbons) or shrank more considerably. These characteristics contributed to intensified compaction of lignite in the briquetting and suppression of the formation of large pores, which are a cause of coke fracture. Two empirical equations, predicting the coke strength from the parameters of lignite properties, were established to be criteria for selection of lignite as HBC coke feedstock, although further investigation with more experimental data would be necessary for the validation.

    更新日期:2017-11-16
  • Inhibitive Effects of Antioxidants on Coal Spontaneous Combustion
    Energy Fuels (IF 3.091) Pub Date : 2017-11-15
    Jinhu Li, Zenghua Li, Yongliang Yang, Xiaoyan Zhang, Daocheng Yan, Liwei Liu

    Based on the deep study of the mechanism of coal spontaneous combustion, this paper proposes new efficient inhibitors preventing coal spontaneous combustion from the perspective of inhibition of free-radical chain reactions. Chifeng coal samples were used as the research object, and six different types of antioxidants were selected as the inhibitor for low-temperature oxidation experiments. A comparison study of the gas product concentration before and after inhibition was conducted; its inhibition mechanism was also studied and analyzed. On the basis of this, the specific indicators, such as cross-point temperature (CPT), apparent activation energy, active functional groups, and an inhibitory rate at 100 °C were used to compare the inhibition effect of antioxidants. The experiments indicate that, except for oxygen-scavenger ascorbic acid, another five antioxidants (butylated hydroxytoluene, BHT; triphenyl phosphite, TPPI; 2,2,6,6-tetramethyl-1-piperidine-noxyl free radical, TEMPO; edetic acid, EDTA; and phytic acid, PA) exhibit a good inhibition effect, and the order of inhibitory effect is RTEMPO> RBHT> REDTA> RTPPI> RPA, indicating that TEMPO has the best inhibition effect with the activation energy of coal oxidation increased by 14.79 kJ·mol–1, and the inhibition rate reached 73.08%. The research results provide new ideas for the prevention and control of coal spontaneous combustion.

    更新日期:2017-11-15
  • Molecular Representation of Petroleum Residues Using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry and Conventional Analysis
    Energy Fuels (IF 3.091) Pub Date : 2017-11-15
    Claudia X. Ramírez, Juan E. Torres, Diana Catalina Palacio Lozano, Juan P. Arenas-Diaz, Enrique Mejia-Ospino, Viatcheslav Kafarov, Alexander Guzman, Jorge Ancheyta

    A methodology for structurally representing the molecules of three Colombian vacuum residues (538+ °C) and one Mexican atmospheric residue (300+ °C) is reported. Information obtained by Fourier transform ion cyclotron resonance mass spectrometry coupled to positive electrospray ionization, negative electrospray ionization, and positive atmospheric pressure photoionization sources and conventional standardized analytical methods was used for molecular representation of the samples. The generation of molecules was performed by a Monte Carlo technique, obtaining a set of representative structures for the global representation through attributes for each residue. The structural attributes considered are CH, CH2, and CH3 in paraffinic chains, number of naphthenic rings, CH2 and CH naphthenic number of aromatic rings, aromatic carbon type, cata- and peri-condensed carbons, number of sheets in asphaltenes, −SH, aromatic S (thiophene), aromatic N (pyridine and pyrrole), and −NH2. Each attribute in the residues can be represented by a probability density function (PDF), which is optimized for the purpose of adjusting the structures of residues and their composition to the experimental data. The PDFs for aromatics and nitrogen and sulfur components were obtained by ultrahigh mass resolution data. As a result, 150 molecules per each residue were obtained, and the mode of representation was single-feed (only one feed is characterized at the same time). The bulk properties for each residue were in good agreement with the experimental structural information.

    更新日期:2017-11-15
  • Wettability Alteration Study of Supercritical CO2 Fracturing Fluid on Low Permeability Oil Reservoir
    Energy Fuels (IF 3.091) Pub Date : 2017-11-15
    Xin Sun, Caili Dai, Yongpeng Sun, Mingyong Du, Tao Wang, Chenwei Zou, Jiayuan He

    Hydraulic fracturing has become an important stimulation technique for low/ultralow permeability reservoirs. Supercritical CO2 (SC-CO2), as a no water phase material of fracturing fluid, receives wide attention. Current researches on SC-CO2 fracturing fluid has mainly focused on its viscous properties and superiorities. However, little attention has been devoted to the interaction between SC-CO2 fracturing fluid and the oil reservoir during the fracturing process. Besides, in a low permeability reservoir, the wettability determines the oil recovery by imbibition, which is a main way to explore oil for a matrix. Therefore, it is crucial to study the wettability alteration on a low permeability oil reservoir introduced by SC-CO2 fracturing fluid. In this study, a contact angle goniometer was introduced to characterize the wettability alteration on low permeability cores by SC-CO2 fracturing fluid. Meanwhile, nuclear magnetic resonance T2 spectra, a scanning electron microscope, and a energy dispersive spectrometer were used to explain the mechanisms of wettability alteration and the adsorption of fracturing fluid was analyzed. In addition, spontaneous imbibition tests were conducted to definite the impact of wettability alteration on oil production. The results showed that the thickener in SC-CO2 fracturing fluid, fluid filter loss, and reservoir permeability were all responsible for wettability alteration on the core surface. With the increasing thickener contents and filter loss of fracturing fluid, cores turned to be intermediate and slightly water-wet from initial strongly water-wet, which was unfavorable for oil production.Comparatively low permeability cores which consist of more micro-small pores were more likely to make treated cores oleophilic, as well. Thickener adsorption was confirmed to be the main mechanism on wettability alteration by SC-CO2 fracturing fluid, which resulted in different pore surfaces, and thus a more oleophilic cores surface. On the basis of the results of spontaneous imbibition, strong lipophilicity cores corresponded to lower oil recovery, which illustrated that wettability alteration caused by SC-CO2 fracturing fluid was not favored for oil flow.

    更新日期:2017-11-15
  • N2O Formation Characteristics in Dielectric Barrier Discharge Reactor for Environmental Application: Effect of Operating Parameters
    Energy Fuels (IF 3.091) Pub Date : 2017-11-14
    Xiaolong Tang, Jiangen Wang, Honghong Yi, Shunzheng Zhao, Fengyu Gao, Yonghai Huang, Runcao Zhang, Zhongyu Yang

    The present study is devoted to the investigation of N2O formation characteristics in dielectric barrier discharge (DBD) reactor for environmental application. The effect of operating parameters, such as specific energy density (SED), O2 concentration, NO initial concentration, and residence time on N2O concentration was investigated in dry O2/N2 mixtures. N2O formation from bulk gas (O2 and N2) is inevitable in DBD chemical process and was observed in all DBD reactors. N2O concentration shows an exponential increase or decrease with the variation in operating parameter. The experimental results show that N2O concentration first increases and then reaches saturation with the increase in SED and O2 concentration, respectively. N2O concentration shows a monotonic increase with increasing residence time. N2O concentration decreases with NO concentration increasing from 50 ppm to 600 ppm. The N2O formation is enhanced with γ-Al2O3 pellets packing into the DBD reactor compared with that of DBD reactor alone.

    更新日期:2017-11-15
  • Functional-group in-situ evolution principles of produced solid and product distribution in biomass torrefaction process
    Energy Fuels (IF 3.091) Pub Date : 2017-11-15
    Huiyan Zhang, Shanshan Shao, Georgy Ryabov, Yang Jiang, Rui Xiao

    Low-temperature pyrolysis (torrefaction) is the first step for combustion. The produced vapors and solids undergo the combustion with different mechanism. So the composition of the vapors and the functional-groups of the produced solids are very important for combustion since they directly influence the diffusion and transfer of oxygen. In this paper, low-temperature pyrolysis of pinewood was studied in a fixed-bed reactor and also by in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Effect of temperature, flow rate of nitrogen and atmosphere was considered to understand the distribution and property of gas, liquid and solid. In-situ DRIFTS was used to monitor the evolution of functional group on the biomass during low-temperature pyrolysis. The results indicated that temperature was the dominant factor that influenced product formation. Gas release were mainly CO and CO2 and their yield promoted with increasing temperature, while non-condensable volatiles contained acetic acids and furans when temperature was lower than 250 °C and higher temperature favored the formation of guaiacols. Characteristic peaks of anhydrides and carboxylic acids showed an irreversible change in the heating and cooling stage, and the change of benzenes can be recovered when cooling down to room temperature. This study investigated the evolution of functional groups of biomass during low-temperature pyrolysis, which provided solid feedstock with appropriate chemical structure for combustion.

    更新日期:2017-11-15
  • Evolution of Chlorine-bearing Gases during Corn Straw Torrefaction at Different Temperatures
    Energy Fuels (IF 3.091) Pub Date : 2017-11-15
    Xiaohan Ren, Emad Rokni, Rui Sun, Xiaoxiao Meng, Yiannis Angelo Levendis

    Release of chlorine during combustion of raw biomass in boilers is detrimental as it contributes to slagging, fouling and corrosion. Combustion of torrefied biomass can alleviate such issues, as it contains less chlorine than its raw biomass precursor. This work assessed the effect of the furnace temperature on the chlorine content of generated torrefied biomass and the released gaseous species during the torrefaction process (a mild pyrolysis). The selected biomass was corn straw, which was torrefied at furnace temperatures, in the range of 250 - 400 °C, under atmospheric pressure in an inert nitrogen flow. Upon torrrefaction, corn straw lost 32-50% of its original mass, to the gas phase, accompanied by more than half of its original mass of chlorine in nearly all cases. The major chlorinated species in the evolving pyrolysis gas (“torgas”) were identified as CH3Cl and HCl. The former was more prevalent at the lower temperatures (<350 °C), whereas the latter dominated at the highest temperature (400 °C). Finally, emissions of other released gases, such as CO, CO2, C2H6, NOx, HCN and NH3 were also monitored and reported herein.

    更新日期:2017-11-15
  • Thermal analysis coupled to ultra high resolution mass spectrometry with collision induced dissociation for complex petroleum samples – heavy oil composition and asphaltene precipitation effects
    Energy Fuels (IF 3.091) Pub Date : 2017-11-14
    Christopher Paul Rüger, Anika Neumann, Martin Sklorz, Theo Schwemer, Ralf Zimmermann

    Thermal desorption and pyrolysis of various heavy oils and asphaltenes (precipitated with different paraffinic solvents) were studied. For this purpose evolved gas analysis was realized by hyphenation of a thermo balance to ultra high-resolution mass spectrometry (FT-ICR MS). The chemical pattern was preserved by applying soft atmospheric pressure chemical ionization (APCI). Collision induced dissociation (CID) was performed for deeper structural insights. Viscous or solid petroleum samples and fractions can be easily measured by the setup. The SARA fractions, deployed for evaluation purposes, revealed a very complex molecular pattern, and fractionation drastically increased the number of assigned elemental compositions. Species from 150—700 m/z and two main phases (desorption and pyrolysis), which transits at roughly 300—350 °C, are observed. Both phases overlap partially but can be separated by applying matrix factorization. The heavy oil and asphaltene mass spectra are dominated by CH-, CHS- and CHN-class compounds, whereas for the CID spectra a lower abundance of oxygenated species was found. Furthermore, physico-chemical properties and the molecular response were correlated for the heavy oils and asphaltene samples, finding a strong correlation between sulfur content and abundance of CHSx-class compounds as well as between DBE and API gravity. As the CID leads mainly to dealkylation, the length of alkylated side chains of components evolved thermally or by pyrolytic processes can be traced during the temperature ramp. In general, an increase of dealkylation in the desorption-phase, followed by a decrease during the transition to pyrolysis and an increase reaching a stable plateau for stable pyrolysis was detected. This behavior was found to be similar for all asphaltenes and for the mean DBE progression. Deploying a lighter paraffinic solvent for asphaltenes precipitation causes a higher abundance species emitted in the desorption phase. They belong mainly to CHOx-class compounds from the maltene fraction occluded and co-precipitated with the asphaltenes. Besides this, no significant effect of the precipitation solvent on the asphaltenic core structures and molecular pattern in the pyrolysis phase was observed. The DBE distribution suggests the presence of the archipelago asphaltenes molecular architecture.

    更新日期:2017-11-15
  • Experimental studies on the effect of tertiary amine promoters in aqueous Monoethanolamine (MEA) solutions on the absorption/stripping performances in Post-Combustion CO2 Capture
    Energy Fuels (IF 3.091) Pub Date : 2017-11-14
    Hongxia Gao, Zeyang Wu, Helei Liu, Xiao Luo, ZhiWu Liang

    The absorption/desorption performance of carbon dioxide (CO2) in aqueous 5M monoethanolamine (MEA) solutions in the presence of various solution regeneration promoters were comprehensively investigated using a multiple rapid screening method. The promoters considered were N-methyldiethanolamine (MDEA), N,N-Dimethylethanolamine (DMEA), N,N‑Diethylethanolamine (DEEA), 1-Dimethylamino-2-propanol(1DMA2P), 1-Diethylamino-2-Propanol(1DEA2P), 3-Dimethylamino-1-propanol (3DMA1P), 2-(Dimethylamino)-2-methyl-1-propanol (2DMA2M1P), Triethanolamine(TEA), 3-(Dimethylamino)-1,2-Propanediol (3DMA-1,2-PD) and 3-(Diethylamino)-1,2-Propanediol (3DEA-1,2-PD). The molar concentration of these promoters added into 5M MEA were set to 1 mol/L. At the atmospheric pressure, the absorption and stripping experiments were carried out at 313.15K and 353.15K, respectively. Especially, the CO2 partial pressure was controlled at constant 15kPa for absorption experiments. In addition, the equilibrium solubility of CO2 was also determined in order to evaluate the driving force of each amine system. The results showed that the highest CO2 equilibrium solubility of 0.5548 mol CO2/mol amine was obtained by MEA/1DEA2P whereas both the fastest absorption and regeneration rates were achieved for aqueous blended MEA/1DMA2P solution which made MEA/1DMA2P to exhibit the highest CO2 cyclic capacity of 1.6710 mol CO2/L.

    更新日期:2017-11-15
  • Bio-oil production by thermochemical catalytic liquefaction of bloom-forming cyanobacteria: Optimization using response surface methodology (RSM)
    Energy Fuels (IF 3.091) Pub Date : 2017-11-14
    Fanghua Li, Zhiquan Hu, Bo Xiao

    Experimental research on thermochemical catalytic liquefaction of bloom-forming cyanobacteria (BC) was carried out to determine the effects of solvent, catalyst, reaction time, temperature, the ratio of raw material to solvent and catalyst dosage on liquefaction performance. The liquefaction conditions were optimized by central composite design (CCD) experiments as follows: the concentrated H2SO4 content of 6.6%, the reaction temperature of 175°C, the reaction time of 30 min and the ratio of material to solvent of 1:4. The liquefaction yield and oil yield (chloroform phase) reached 93.85% and 37.96% at above-mentioned conditions. The ultimate analysis and calorific value of the oil were determined, and the chemical composition of the oil was investigated using gas chromatography-mass spectrometry (GC-MS) technique and Fourier-transform infrared (FT-IR) spectroscopy. The analysis of bio-oil composition showed that bio-oil from BC mainly contains ethyl palmitate which is the main composition of palm oil biodiesel, with a heating value of 32.7MJ/kg.

    更新日期:2017-11-15
  • Characterization of CO2 absorption and carbamate precipitate in phase-change MAPA/DMF solvent
    Energy Fuels (IF 3.091) Pub Date : 2017-11-14
    Jun Cheng, Yannan Li, Leiqing Hu, Jianzhong Liu, Junhu Zhou, Kefa Cen

    A phase-change solvent for CO2 absorption was prepared by mixing N-methyl-1,3-diaminopropane (MAPA) and N,N-dimethylformamide (DMF). In this MAPA/DMF solvent, MAPA–carbamate precipitate was formed after CO2 absorption to facilitate reducing energy consumption of amine regeneration. The CO2 uptake of MAPA/DMF solvent (14.8 mg/g solvent) was increased by 22% compared with that of MAPA/water solvent (12.1 mg/g solvent). For MAPA/DMF solvent, time was reduced by 22% to reach the CO2 absorption equilibrium. The maximum CO2 uptake rate of MAPA/DMF solvent was 30% higher than that of MAPA/water solvent because DMF displayed higher CO2 solubility and lower MAPA–carbamate solubility than water. Differential scanning calorimetry and thermogravimetry experiments revealed that MAPA(H+)2 and MAPA(CO2−)2 compositions in MAPA–carbamate precipitate first decomposed (peak temperature = 59.9 °C). Subsequently, the MAPACO2 compositions in precipitate also decomposed (peak temperature = 124.2 °C).

    更新日期:2017-11-15
  • A molecular dynamics investigation on coke ash behaviour in the high temperature zones of a blast furnace: Influence of alkalis
    Energy Fuels (IF 3.091) Pub Date : 2017-11-14
    Kejiang Li, Rita Khanna, Jianliang Zhang, Mohammed Bouhadja, Minmin Sun, Mansoor Barati, Zhengjian Liu, Chandra Veer Singh

    With specific focus on local structural order, bonding networks, transport properties and viscosity of the molten ash oxides, we report molecular dynamics simulations on the influence of alkalis (Na2O and K2O) on coke behavior within a blast furnace. Atomistic simulations were carried out on the Al2O3-SiO2-CaO-K2O-Na2O system at 2223 K for a range and relative proportions of Na2O and K2O. Alkalis were seen to have a strong effect on the oxygen bonding networks; the relative proportions of bridging and non-bridging oxygen showed a sharp increase while significant reductions were observed for tri-cluster oxygens. Total diffusion coefficients and viscosity showed a highly non-linear dependence on the relative proportions of two alkalis with large changes observed in the simultaneous presence of alkalis as compared to their individual presence. Our studies have shown that the combined influence of alkalis on the viscosity of molten ash, and associated coke degradation within a blast furnace is likely to be much smaller than previously perceived, and could even be negligible for some alkali concentrations.

    更新日期:2017-11-15
  • A pH-resolved Wettability Alteration: Implications for CO2-assisted EOR in Carbonate Reservoirs
    Energy Fuels (IF 3.091) Pub Date : 2017-11-14
    Quan Xie, Yongqiang Chen, Ahmad Sari, Wan-Fen Pu, Ali Saeedi, Xinwei Liao

    Wettability of oil/brine/rock system is a critical petro-physical parameter, which governs subsurface multiphase flow behavior, thus hydrocarbon recovery. While the mechanisms of CO2-assisted enhanced oil recovery (EOR) techniques have been extensively investigated in carbonate reservoirs, few have done to identify the controlling factor of CO2-induced wettability alteration, and fewer have look beyond the implications for CO2-assisted EOR. We thus hypothesize that CO2-assisted EOR techniques cause a more hydrophilic system due to H+ adsorption on the interface of oil/brine and brine/carbonate as a result of CO2 dissolution. To test this hypothesis, we measured contact angles of two oils with different acid and base number in the presence of 1M Na2SO4 at pH either 3 or 8. Moreover, we performed a geochemical study to identify the controlling factor of wettability alteration. Contact angle results support the hypothesis, showing that the oil/brine/rock system shifts towards more water-wet because of less bonds between oil/brine and brine/carbonate due to H+ adsorption on the interface of oil/brine and brine/carbonate. Our results also suggest that CO2-assisted EOR techniques likely shift relative permeability curves towards a lower residual oil saturation due to wettability alteration. We argue that geochemical reactions may need to be incorporated into reservoir numerical model, thus better managing and predicting the performance of CO2-assisted EOR.

    更新日期:2017-11-15
  • A Model of Lignite Macromolecular Structures and Its Effect on the Wettability of Coal: A Case Study
    Energy Fuels (IF 3.091) Pub Date : 2017-11-13
    Weimin Cheng, Jiao Xue, Jun Xie, Gang Zhou, Wen Nie

    Chemical and physical structure properties of coal macromolecules are the main microscopic factors affecting coal wettability. Numerous studies on coal structures have found that lignite, as a coal of low metamorphic degree, shows more-complicated macromolecular structures than other types of coal, and the macromolecular structure of lignite can better promote coal wettability than other low metamorphic coals with similar physical pore structures. To investigate the underlying reasons, lignite samples from the main coal producing areas of China were analyzed via X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy, and physical methods were used to construct two-dimensional and three-dimensional models of lignite macroscopic molecular structures to study its effect on coal wettability. The results indicated that aromatic layer spacing of lignite was considerably large and showed a low degree of aromatization with irregular arrangement and less directional degree. The macroscopic molecular structure of lignite was composed of 3–4 effectively stacked aromatic layers and alicyclic layers of hexagonal or pentagonal structures. The alicyclic ring structure was well-developed in the atom radial direction and had a high content of active ingredient, which was prone to attractive interaction with other molecules. The molecular formula of the lignite sample was determined to be C180H145O31N5S and the adsorption and spreading of wetting agents were found to be mainly dependent on the hydrophilic ability of coal surface. Furthermore, the microscopic pore stacking stereochemical structure of lignite indicated the existence of hydrophilic groups in surface functional groups around molecular nucleus, which resulted in the formation of infiltration points in the coal crystallite nucleus structure. Meanwhile, the absence of delocalized electron in the atom radial direction of amorphous lignite atoms could induce a relatively poor ability of attracting negative charge, and thus lessening the repulsive interaction to the electronegative ions in aqueous solutions, which promoted the wetting effect to some extent.

    更新日期:2017-11-14
  • Influence of Addition of a High Amount of Calcium Oxide on the Yields of Pyrolysis Products and Noncondensable Gas Evolving during Corn Stalk Pyrolysis
    Energy Fuels (IF 3.091) Pub Date : 2017-11-13
    Bin Li, Haiping Yang, Biao Liu, Liangyuan Wei, Jingai Shao, Hanping Chen

    The effects of addition of a high amount of CaO on the yields of pyrolysis products and the evolving of noncondensable gas from corn stalk pyrolysis at different temperatures were investigated using a fixed-bed pyrolysis system. The results showed that almost all the CO2 generated during the pyrolysis process could be absorbed by CaO (CaO/C = 1) at a lower temperature of 550–650 °C, and a low CO2 concentration of only 0–0.7 vol % was obtained in the noncondensable gas. The CO2 fixation into the solid phase (CaCO3) caused a big decrease in noncondensable gas yield and a significant increase in H2 concentration. Furthermore, CaO addition could catalyze the pyrolysis process and intensify the secondary pyrolysis of volatiles to produce more H2 and CH4. The higher heating value of noncondensable gas could achieve 19.3 MJ/m3 at 550 °C. However, beyond 700 °C (700–850 °C), the CO2 absorption capability of CaO declined greatly and the CO2 in the noncondensable gas increased obviously, but CaO addition could still inhibit the CO2 generation compared with the trials without CaO addition. Moreover, the catalytic effect of CaO was much more significant at higher temperature in corn stalk pyrolysis. The yields of H2 and CO increased greatly compared with those without CaO addition. The yields of CH4 and C2+ also increased and then decreased at 850 °C due to the thermal decomposition.

    更新日期:2017-11-14
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.
化学 · 材料 期刊列表