Rational Design of Hydrogen-Donor Solvents for Direct Coal Liquefaction Energy Fuels (IF 3.091) Pub Date : 2018-03-20 Peidong Hou, Yuwei Zhou, Wenping Guo, Pengju Ren, Qiang Guo, Hongwei Xiang, Yong-Wang Li, Xiao-Dong Wen, Yong Yang
Facing the challenge of processes in direct coal liquefaction (DCL), it is vital to develop optimal hydrogen-donor solvent (H-donor) to dramatically moderate coal liquefaction conditions. Here, we propose an approach for rational design of optimal H-donor candidates based on density functional theory (DFT) calculations combining reverse searching algorithm. First, the mechanism of hydrogen transfer from H-donor to coal radical was investigated by using common model compounds. DFT calculations show that the concerted hydrogen transfer route promoted by coal radicals is the dominant pathway. The C–H bond dissociation enthalpies (BDEs) show strong correlation with intrinsic reaction barriers and rate constants (in log scale), which allow us to define a cheap metric for comparing the hydrogen-donation ability of different H-donors. Then the framework for rational design of H-donor candidates is established to seek molecules with low C–H BDEs based on inverse molecular design strategy. In the searching procedure, the chemical structure of parent molecule is varied by appropriate substituent from a predefined library (15 substituents). To reduce searching space, four empirical rules are proposed to guide the structural modifications. Finally, the H-donor candidates designed are validated by transition state calculations. It is confirmed that the inverse molecular design approach is effective for seeking candidate H-donors with lower reaction barriers and potentially higher rate of hydrogenation, which open a window for the rational design of optimal H-donors to improve the yields of the liquid products from coal under mild conditions.
Effects of In-Process Hydrogenation on Mesophase Development during the Thermal Condensation of Petroleum Aromatic-Rich Fraction Energy Fuels (IF 3.091) Pub Date : 2018-03-19 Ming Li, Yadong Zhang, Shitao Yu, Junwei Ding, Bing Bian, Dong Liu
In this work, the mesophase pitch was generated from the thermal condensation of the petroleum aromatic-rich fraction. Tetrahydronaphthalene as a hydrogen donor was selected to treat the condensation intermediate using the in-process hydrogenation method. The objective of this work was to investigate the effects of in-process hydrogenation on the formation and development of mesophase structures. Results showed that the intermediate after in-process hydrogenation possessed a more-uniform molecular structure and narrower molecular-weight distribution, compared to the blank intermediate without in-process hydrogenation, which was attributed to the increasing content of naphthenic structures in the intermediate. From the characterization analysis of carbonized products, it can be found that the in-process hydrogenation of the condensation intermediate was conducive to the generation of mesophase pitch with a large domain structure, narrow molecular-weight distribution, low softening point, and carbon residue.
Predicted Effects of Heavy Feeds on the Deactivation of a Commercial Atmospheric Residue Desulfurization Catalyst System Energy Fuels (IF 3.091) Pub Date : 2018-03-19 Dduha Chehadeh, Hamza Albazzaz, Dawoud Bahzad
The effect of three atmospheric residual oils on the deactivation of a commercial atmospheric residue desulfurization (ARDS) catalyst system was assessed using a commercial catalyst system consisting of five catalysts loaded inside a two-reactor pilot plant. The hydrodemetalation (HDM) and hydrodesulfurization (HDS) reactions of the three residues over the catalyst system were studied. A deactivation model considering metals and carbon deposition was used to fit the life test data. Experimental and simulated data were compared. The effect of the residual oils on each of the catalysts was evaluated, and the catalyst contribution was calculated highlighting the importance of predicting different catalyst activities during the design of a composite catalyst bed.
Effect of compression ratio on combustion performance and emission characteristic of a DI diesel engine fueled with upgraded biogas-KME-DEE port injection Energy Fuels (IF 3.091) Pub Date : 2018-03-19 Debabrata Barik, Asit Kumar, S. Murugan
This work is an attempt to divulge the influence of compression ratio (CR) on the behavior of a 4.4 kW, single cylinder, air-cooled, diesel engine operated on up-graded biogas-Karanja methyl ester (UBG-KME) dual fuel. Earlier, experiment was conducted by the authors to examine the use of UBG-KME-DEE (diethyl ether) in a dual fuel engine, and the results indicate that, UBG-KME-DEE port injection functioned well and provided improved performance and lower emissions in comparison to that of the raw biogas (RBG) RBG-KME-DEE mode. Nevertheless, the engine produced a lower brake thermal efficiency (BTE) compared to that of diesel operation. Hence, to increase the BTE, experiments were conducted with varied CRs (16.5, 17.5, and 18.5) of the engine, and the KME was injected at a fixed timing of 24.5 oCA bTDC, DEE supply to engine was limited at 6%, and the upgraded biogas supply was made constant at 0.9 kg/h. The test results indicated that UBG-KME-DEE operation with CR 18.5 gave optimum results than those of other CRs. An increase in heat release rate of 60 J/o CA, and shorter ignition delay of 7.8 oCA was observed for UBG-KME-DEE operation with CR 18.5, at full operating load. BTE was increased, and BSEC was decreased by about 7% and 6.8%, respectively, for UBG-KME-DEE operation with CR 18.5 in comparison with KME. About 44, 42, and 42.8% decrease in the emissions of CO, HC, and smoke were observed for UBG-KME-DEE at CR 18.5. However, the emission of NO for UBG-KME-DEE operation with CR 18.5 was 7.6% higher than diesel but, 1.2% lower than KME, at full operating load. The novel findings of this study make possibilities of lowering the NO-smoke emission trade-off, which is a prime challenge in diesel engines. In addition, the upgraded biogas-KME-DEE operated diesel engines (renewable nature) can substitute the use of diesel and CNG.
Roles of cation and anion of amino acid anion-functionalized ionic liquids immobilized into a porous support for CO2 capture Energy Fuels (IF 3.091) Pub Date : 2018-03-19 Yusuke Uehara, Davood Karami, Nader Mahinpey
The impact of cation and anion of amino acid (AA) anion-functionalized ionic liquids (ILs) immobilized into a porous support on the CO2 capture performance was investigated in dry or humidified gas flow condition. 1-ethyl-3-methylimidazolium ([EMIM]) cation and tetrabutylphosphonium ([P4444]) cation were used as a cation for synthesizing AAILs and compared, since they have different molecular structures and hydrophilicities with each other affecting gas sorption behaviors. The experimental results showed that supported [P4444][AAs] had higher CO2 capture capacities than the corresponding supported [EMIM][AAs] in units of mol/mol-AAIL under dry gas inlet, exhibiting the effect of cation on the CO2 adsorption performance. Under humidified gas flow, supported [P4444][AAs] adsorbed much less amounts of water vapor than supported [EMIM][AAs]. On the other hand, CO2 capture capacities of both supported [EMIM][AAs] and [P4444][AAs] slightly reduced in the presence of water vapor, due to much more rapid sorption of H2O than CO2.
Fractionating Wheat Straw via PHP (Phosphoric Acid plus Hydrogen Peroxide) Pretreatment and Structural Elucidation of the Derived Lignin Energy Fuels (IF 3.091) Pub Date : 2018-03-19 Xue Wan, Dong Tian, Fei Shen, Jinguang Hu, Gang Yang, Yanzong Zhang, Shihuai Deng, Jing Zhang, Yongmei Zeng
As a new-developed method for pretreating lignocellulosic biomass, PHP (phosphoric acid plus hydrogen peroxide) was employed as a pretreatment solvent to fractionate wheat straw. The structural properties of the derived lignin were elucidated in particular. Results indicated 100.0 g wheat straw (dry basis) yielded 39.7 g cellulose-rich fraction, 4.7 g oligosaccharides and 4.5 g lignin at mild conditions of 50 °C within 1.0 h. The resultant cellulose-rich fraction was highly accessible to hydrolytic enzymes with 88-96% cellulose-glucose conversion in 24 h, suggesting a great potential for producing biofuels. The derived lignin was characterized by high purity (≤1.0% residual carbohydrates), relatively low molecular weight (Mw < 1436 g mol-1), and abundant in carboxylic acid functional groups. According to the 31P, 13C and 2D-HSQC NMR results on the derived lignin, the degree of condensation was quite limited during PHP pretreatment, the oxidants, produced HO+ or HO· in pretreatment, were substantially responsible for the extensive ring-opening on the aromatic substructure. The obtained results offered the technical feasibility of fractionating lignocellulosic biomass using PHP, and a better understanding of the delignification mechanisms for PHP pretreatment.
A novel mesoporous SiO2 material with MCM-41 structure from coal gangue: preparation, ethylenediamine-modification, and adsorption properties for CO2 capture Energy Fuels (IF 3.091) Pub Date : 2018-03-19 Hong Du, Liang Ma, Xiaoyao Liu, Fei Zhang, Xinyu Yang, Yu Wu, Jianbin Zhang
A novel mesoporous SiO2 material (M-SiO2) with MCM-41 structure was readily fabricated from the inexpensive coal gangue via hydrothermal reaction in the presence of cetyltrimethyl ammonium bromide (CTAB) for CO2 capture. Based on orthogonal experimental results, the optimum conditions for the preparation of M-SiO2 were identified as follows: the SiO32- leaching of 21 g/L from coal gangue, the CTAB concentration of 0.25 mol/L, the HCl concentration of 2.5 mol/L, the hydrothermal temperature of 393.15 K, and the hydrothermal time of 20 h. Under the optimum condition, the M-SiO2 exhibited an adsorption capability of 9.61 mg/g to 8 % CO2 at 298.15 K. To further improve the CO2 adsorption performance, the M-SiO2 was chemically modified using ethylenediamine (EDA), and the optimum conditions for the modification of M-SiO2 were identified as follows: the impregnation time of 10 h, the drying temperature of 343.15 K, and the ratio of EDA: M-SiO2 = 2: 1. Under the optimum conditions, the adsorption capability of EDA-modified M-SiO2 (EDA-M-SiO2) was increased by 83.5 mg/g. The obtained M-SiO2 and EDA-M-SiO2 were systemically characterized by N2 adsorption-desorption isotherms, thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction measurements techniques. The analytical results indicated that the M-SiO2 was mainly composed of O and Si in the form of SiO2 with a specific surface area of 156 m2/g, and part of M-SiO2 exhibited a similar structure to MCM-41. Moreover, the mechanisms of EDA-modification and CO2 adsorption were investigated and discussed in detail.
CO2 Uptake Potential of Ca-based Air Pollution Control (APC) Residues over Repeated Carbonation/Calcination Cycles Energy Fuels (IF 3.091) Pub Date : 2018-03-19 Alessandro Dal Pozzo, Andac Armutlulu, Margarita Rekhtina, Christoph R. Müller, Valerio Cozzani
Operation of dry processes for acid gas removal from flue gas in waste-to-energy plants based on the use of calcium hydroxide as a solid sorbent generates a solid waste stream containing fly ash, unreacted calcium hydroxide and the products of its reaction with acid pollutants in the flue gas (HCl and SO2). To date, the fate of the solid waste stream is to be landfilled, in the absence of commercially viable recycling approaches. The present study investigates the potential of these residues as CO2 sorbents in the calcium looping process. Samples collected in different waste-to-energy plants were tested over multiple carbonation/calcination cycles, comparing their performance to that of limestone. Though inferior, the CO2 sorption capacity of the residues resulted comparable to that of limestone, and steadily increased for a significant number of cycles. This peculiar behavior was attributed to the presence of a chlorinated phase which enhances the CO2 uptake in the diffusion-controlled stage of carbonation, by reducing the product layer resistance to CO2 diffusion. No significant release of acid gases was observed at the characteristic temperatures of calcium looping carbonation.
Adsorption of CO2 on MgAl-CO3 LDHs-Derived Sorbents with 3D Nanoflower-like Structure Energy Fuels (IF 3.091) Pub Date : 2018-03-19 Xiaochen Kou, Hongxia Guo, Etsegenet Gossa Ayele, Shan Li, Yujun Zhao, Shengping Wang, Xinbin Ma
In this paper, the porous MgAl-CO3 LDHs-derived mixed oxides with Mg/Al molar ratios of 2:1, 2.5:1, 3:1, 3.5:1, and 4:1 have been successfully prepared by a facile solvothermal method. With a 3D nanoflower-like structure, the MgAl-CO3 LDHs-derived mixed oxides with a Mg/Al molar ratio of 2 exhibit the best CO2 sorption performance of about 0.9 mmol/g at the adsorption temperature of 200 °C. The addition of NaNO3 into the MgAl-CO3 LDHs-derived mixed oxides (Mg/Al = 2:1) can facilitate the sorption process by reducing the energy barrier between MgO and MgCO3. Introducing methanol to the preparation process of LDHs prior to drying can effectively increase the specific surface area and improve the porosity of the sorbents by substituting the water molecules of MgAl-CO3 LDHs. The sorbents co-modified by NaNO3 and methanol with a Mg/Al molar ratio of 2 show the favorable sorption performance with the CO2 uptake of 1.70 mmol/g over 100 sorption/desorption cycles about 300 h.
Separation of Viscous Oil Emulsions Using Three-Dimensional Nanotetrapodal ZnO Membranes Energy Fuels (IF 3.091) Pub Date : 2018-03-19 Thomas E. O’Loughlin, Frank-Eric Ngamassi, Patrick McKay, Sarbajit Banerjee
Unveiling Adsorption Mechanisms of Elemental Mercury on Defective Boron Nitride Monolayer: A Computational Study Energy Fuels (IF 3.091) Pub Date : 2018-03-19 Xiaoping Gao, Yanan Zhou, Yujia Tan, Zhiwen Cheng, Qingli Tang, Jinping Jia, Zhemin Shen
The control of mercury in flue gas is challenging, especially that of elemental mercury (Hg0). Recently, many researchers have focused on various mercury removal technologies. Here by performing density functional theory (DFT) calculations, we systematically studied the adsorption of Hg0 on several experimentally available hexagonal boron nitride (h-BN) nanosheets with defect-free, nitrogen vacancy (VN), boron vacancy (VB), and both nitride and boron vacancy (VN+B) as well as their structures and electronic properties. Our calculation results show that the presence of VN, VB, and VN+B vacancies enhances the adsorption energies of Hg0 by 9, 45, and 214 kJ/mol, respectively. Moreover, a more negative potential at the VB and VN+B vacancy sites results in the h-BN-VB and h-BN-VN+B surfaces more reactive than those of h-BN and h-BN-VN. The partial density of states (PDOS) analysis unveils that Hg atom interacts firmly with surface B or/and N atoms through the orbital hybridization. The tendency of equilibrium constant implies that adsorption of Hg0 on h-BN-VN+B surface is beneficial at low temperature. Our computational studies reveal that defective h-BN nanosheets with VB and VN+B have great potential to serve as novel sorbents for the efficient removal of mercury in flue gas.
Mercury interaction on modified activated carbons under oxyfuel combustion conditions Energy Fuels (IF 3.091) Pub Date : 2018-03-19 Margarita Quirós-Álvarez, Mercedes Diaz Somoano, Wolfgang Bongartz, Satrugna Vinjarapu
Mercury pollution is a cause for concern that requires global action. The most demonstrated and commercially available technology for mercury control is pulverised activated carbon injection. During oxy-coal combustion, the elevated concentrations of SOx, the moisture level in the flue gas and the recirculation streams may affect the performance of activated carbons as mercury sorbents. This works evaluates mercury oxidation and capture using impregnated-activated carbons. In this study a novel aspect is considered by the application of a novel thermal desorption procedure for mercury species identification and the elucidation of the interaction mechanism. The results show oxidation efficiencies ranging from 85 to 96%. The mercury is partially retained in the solid by chemical adsorption. The formation of new mercury species HgS, HgI2 and HgO by the interaction was established.
2D and 3D Spectrum Graphics of the Chemical-Morphological Domains of Complex Biomass by Low Field Proton NMR Energy Relaxation Signal Analysis Energy Fuels (IF 3.091) Pub Date : 2018-03-18 Zeev Wiesman, Charles Linder, Maysa T Resende, Natan Ayalon, Ofer Levi, Oigres D Bernardinelli, Luiz A Colnago, Cirlei Igreja Nascimento Mitre, Roi Jackman
The present paper describes novel low frequency (LF) 1H NMR energy relaxation time signal analysis for mapping the different chemical and morphological domains in complex cattle manure (CM) and cattle forage (CF) biomass. Relaxation signals generated by different absorbed water pools and aliphatic chains, are analysed by specifically designed sparse representation methods and a convex optimization PDCO solver, for generating 2D T1 (spin-matrix) vs. T2 (spin-spin) energy relaxation time spectrum graphics, and 3D graphs that includes 1H population density. Using analytical spectral analyses and spiking assignment with material standards of the individual T1 vs. T2 peaks in the generated CM graphics, a morphological and chemical domain dictionary was formulated demonstrating well resolved signal peaks and a better understanding of the different chemical and morphological structural organization within the complex biomass material. This bench top proton LF-NMR relaxation sensor system and its signal generation into chemical-morphological spectrum graphics, has the potential to significantly contribute to a rapid and accurate monitoring system for bio-based industrial processes with significant applicability in for example, bio-refineries.
Thermal characteristics of biomass pyrolysis oil and potential hydrogen production by catalytic steam reforming Energy Fuels (IF 3.091) Pub Date : 2018-03-18 Ningbo Gao, Cui Quan, Zhengzhao Ma, Chunfei Wu
: In order to facilitate the further processing and utilization of biomass pyrolysis oil, the chemical composition and thermal properties of biomass pyrolysis oil from pyrolysis of rice husk were investigated. The chemical composition analysis revealed that the pyrolysis oil contained large amount of oxygenated compounds, i.e., acid, ketones and phenols. Thermal degradation behaviors and kinetics of pyrolysis oil were investigated at different heating rates (5, 20, 35 and 50 oC min-1) under N2 and air atmosphere by TG. Pyrolysis oil decomposition mainly experienced three stages either in N2 or air atmosphere, and the corresponding activation energies vary with the degree of conversion. Py-GC/MS analysis of the pyrolysis oil reveals that ketones and aromatics are the main pyrolysis products of biomass pyrolysis oil. When the temperature increased from 600 to 700 oC during Py-GC/MS analysis, the content of ketones increased while the content of aromatics decreased. Subsequently, the feasibility of catalytic steam reforming of pyrolysis oil to produce renewable hydrogen was performed in a fixed-bed reactor with a NiO/ceramic foam catalyst. The effects of calcination temperature and metal content on the hydrogen yield were investigated. It is indicated that higher calcination temperature and loading content lead to the aggregation and sintering of NiO particles. A maximum hydrogen yield of 105.28 g H2 kg-1 pyrolysis oil (up to 81.1% of the stoichiometric yield) was obtained at reaction temperature of 700 oC, S/C ratio of 1, NiO loading content of 3.54%.
Biogas Production and Microbial Community Dynamics during Anaerobic Digestion of Rice Straw at 39 °C–50 °C: A Pilot Study Energy Fuels (IF 3.091) Pub Date : 2018-03-16 Qing Yu, Jun Zhou, Zhenzhen Tian, Jingyuan Liu, Zhiying Yan, Xiaoyu Yong, Honghua Jia, Xiayuan Wu, Ping Wei
The purpose of this study was to investigate the anaerobic digestion (AD) of rice straw at different temperatures in a 300 m3 bioreactor. The results showed that the biogas yield was 401.9 m3/t (dry straw weight) in this AD system. The contents of total solids, volatile solids, chemical oxygen demand, pH, NH4+-N, and volatile fatty acids were all in the optimal range, indicating that the entire AD system was stable and efficient. In addition, Bacteroidetes was the main bacteria during the AD process. When the temperature increased, the relative abundance ratio of Methanoculleus, Methanosarcina, and Firmicutes increased. The phyla Bacteroidetes and Fibrobacteres predominated in straw samples and the relative abundance ratio of Firmicutes and Bacteroidetes in thermophilic AD was much greater than in mesophilic AD. This study provides new evidence regarding the effects of temperature on the community changes of specific microbiota in the AD of rice straw.
Microscopic Mechanism of Clay Minerals on Reservoir Damage during Steam Injection in Unconsolidated Sandstone Energy Fuels (IF 3.091) Pub Date : 2018-03-16 Yan Zhuang, Xiangjun Liu, Hanqiao Xiong, Lixi Liang
In this work, the swelling, transformation, and dissolution of clay minerals after steam injection in heavy oil reservoir were investigated, and the damage mechanism of steam injection was discussed to research the microscopic mechanism of clay minerals on reservoir damage during steam injection in unconsolidated sandstone. The results show that the swelling of clay minerals increases with the increase of the pH of the brine and decreases with the increase of the salinity of the brine. As we all know, the swollen clay minerals are liable to fall from the inner wall of the pass, which may cause the blockage of reservoirs. What is more, the environment of high temperature and high pH would promote the transformation of the clay minerals. Montmorillonite can be transformed into illite and analcime, and kaolinite can be transformed—due to the water sensitivity of the clay mineral—to montmorillonite and analcime, whereas illite is relatively stable. For the movement of particles in the reservoir during the injection of steam, the water sensitivity of clay mineral montmorillonite and the new clay minerals analcime can easily plug the small reservoir pore, which is one of the main ways to cause damage to the reservoir during steam injection. The dissolution of clay minerals increases with the increase of temperature and increases with the increase of the pH of the brine. The dissolution of clay minerals would produce a large number of particles and make the rock matrix more loose, which may cause some reservoir damage, such as reservoir collapse, and so on.
Molecular Fingerprints and Speciation of Crude Oils and Heavy Fractions Revealed by Molecular and Elemental Mass Spectrometry: Keystone between Petroleomics, Metallopetroleomics, and Petrointeractomics Energy Fuels (IF 3.091) Pub Date : 2018-03-15 Sara Gutiérrez Sama, Mathilde Farenc, Caroline Barrère-Mangote, Ryszard Lobinski, Carlos Afonso, Brice Bouyssière, Pierre Giusti
Petroleum and its fractions are some of the most complex mixtures found in analytical chemistry. Mass spectrometry currently plays an increasing role in the characterization of these matrices. Since the last review on this topic in 2011, several new approaches have been introduced, and these approaches increasingly use sample fractionation by extraction and/or liquid chromatographic techniques. This review considers molecular mass spectrometry (with special emphasis on the use of ion mobility) and inorganic mass spectrometry. The combination of both techniques paves the way to “petrointeractomic” approaches, which are introduced as a novel, important part of “petroleomic” approaches.
Fractionation of pyrrolic nitrogen-containing compounds during primary migration of petroleum within the Barnett Shale sequence of Marathon 1 Mesquite Well, Texas Energy Fuels (IF 3.091) Pub Date : 2018-03-15 Yuanjia Han, Stefanie Pötz, Nicolaj Mahlstedt, Cornelia Karger, Brian Horsfield
The primary migration of petroleum has been recently described in detail for a thermally mature core of the Barnett Shale with almost nonvariant organofacies and maturity. Here, we use samples from the same well to provide new insights into the fractionation of pyrrolic nitrogen compounds during primary migration. Using gas chromatography-mass spectrometry (GC-MS), a decrease in concentration of carbazoles and benzocarbazoles was observed which correlated with migration distance. However, a preferential removal of individual isomers like benzocarbazole [a] relative to benzocarbazole [c] could not be detected. Enlarging the analytical window, we studied the effect of primary migration on high molecular weight nitrogen-containing compounds using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) combined with electrospray ionization (ESI) in the negative ion mode. Compounds with one or two nitrogen atoms are most abundant. Amongst the N1 compounds, those with 12, 15, 18, 20 and 23 double bond equivalents (DBEs) were dominating classes representing carbazole-type compounds (amongst others) with one to three ortho-annelated benzene rings (12, 15 and 18) and four to five ortho- and peri-annelated benzene rings (20, 23). In comparison, the N2 compound class mainly consists of compounds with 12, 15, 17, 20 and 23 DBEs representing (amongst other compounds) biindoles with zero to one ortho-annelated benzene ring (12, 15) and carbazolocarbazoles with zero to two ortho-annelated benzene rings (17, 20 and 23). A relative enrichment of biindole-type compounds in comparison to carbazolocarbazoles in migrated petroleum was shown. This might indicate that aromatic compounds with separated ring systems like biindoles are less strong retained in the source rock than fully annelated polycyclic aromatic compounds like carbazolocarbazoles. Within DBE classes of N1 and N2 compounds, very similar carbon number (CN) distributions were illustrated, i.e., a predominance of C0-5 alkylated homologs maximizing at C2 or C3 substitutes. Regardless of fractionation, the overall similar distributions in DBE and CN suggest that pyrrolic nitrogen-containing compounds have restricted precursors and common mechanisms of formation. Nonfluorescent chlorophyll catabolites (NCCs), the final breakdown products of chlorophyll, were tentatively suggested as possible precursors.
Gravitational Gradient of Asphaltene Molecules in an Oilfield Reservoir with Light Oil Energy Fuels (IF 3.091) Pub Date : 2018-03-14 Soraya S. Betancourt, Yngve Bolstad Johansen, Julia C. Forsythe, Joachim Rinna, Kjell Christoffersen, Pål Skillingstad, Vladislav Achourov, Jesus Canas, Li Chen, Andrew E. Pomerantz, Julian Y. Zuo, Oliver C. Mullins
In toluene, asphaltenes are dispersed as molecules at low concentrations, as nanoaggregates at moderate concentrations, and as clusters of nanoaggregates at high concentrations. These three asphaltene species are codified in the Yen–Mullins model. For reservoir crude oils, equilibrated asphaltene gradients can be modeled with the Flory–Huggins–Zuo equation of state (EoS). The gravity term and other terms depend on the particle sizes of the asphaltenes which are given in the Yen–Mullins model; these different asphaltene species (molecular and two nanocolloidal species) have been identified in gravity gradients in various reservoir studies. Here, the asphaltene gradient in a large reservoir is examined and found to be consistent with a molecular dispersion of asphaltenes in the crude oil. A variety of fluid and reservoir properties are evaluated to ensure validity of the analysis, particularly of thermodynamic equilibrium of the reservoir fluid. For crude oil samples throughout the reservoir, downhole fluid analysis (DFA), gas chromatography (GC), and two-dimensional gas chromatography (GC×GC) with cubic EoS and geochemical interpretation are consistent with fluid equilibration. Pressure measurement and production results are also consistent with fluid equilibration. This analysis is applicable to other reservoirs; molecular dispersions of asphaltenes are expected for other light oil reservoirs.
Effect of CO2 on the Interfacial and Transport Properties of Water/Binary and Asphaltenic Oils: Insights from Molecular Dynamics Energy Fuels (IF 3.091) Pub Date : 2018-03-14 Sohaib Mohammed, G.Ali Mansoori
We conducted molecular dynamics (MD) simulations to investigate the effect of supercritical carbon dioxide (sc-CO2) on the interfacial and transport properties of water–oil systems. The oil phase was resembled by employing different binary hydrocarbons (paraffin + aromatic), namely, benzene + hexane, benzene + octane, xylene + hexane, and xylene + octane. Furthermore, we added an asphaltene to the system composed of xylene and hexane to study the interfacial behavior of the heaviest fraction of oil (asphaltene) in the presence of CO2. The simulations were performed under the operating conditions of 100 bar and 350 K. The results showed that aromatics, CO2, and asphaltenes accumulated at the interface at low CO2 mole fractions (xCO2). However, when xCO2 increased, it displaced the aromatics away from the interface and toward the bulk. At very high xCO2, the aromatics accumulated at the oil bulk. Similarly, asphaltene molecules stacked at the interface at low xCO2, and as xCO2 increased, some of the asphaltene molecules dissolved and aggregated in the oil bulk. CO2 forms a film between water and oil phases, and as the thickness of the film increases, it displaces the hydrocarbons away from the interface. The addition of sc-CO2 diluted the interface, formed hydrogen bonds (H bonds) with water, which stabilize the CO2 film, and reduced the interfacial tension in all systems. Furthermore, the addition of sc-CO2 increased the diffusivity of the oil phase in all systems. However, it significantly affected the diffusivity of systems that have less polar aromatics.
Release of Nitrogenous Volatile Species from South African Bituminous Coals during Pyrolysis Energy Fuels (IF 3.091) Pub Date : 2018-03-14 Zebron Phiri, Raymond C. Everson, Hein W. J. P. Neomagus, André D. Engelbrecht, Barry J. Wood, Bonny Nyangwa
The influence of typical South African coal attributes on the release of nitrogen into the volatile stream during pyrolysis was studied by utilizing three bituminous coals. The majority of South African coals are characterized by high mineral matter and are rich in inertinite maceral. Pyrolysis was conducted in a bench-scale fluidized bed (FB) at 740–980 °C, and also in a drop-tube furnace (DTF) at 1000–1400 °C. Levels of nitrogenous species in the volatile stream in the form of NH3, HCN, and tar-N were determined. Nitrogen functional forms of tars released at low temperatures were predominantly distinguished by high levels of pyrrolic nitrogen, followed by pyridinic and quaternary nitrogen, respectively. Tars liberated at 740 °C possessed similar nitrogen functional form attributes as those of parent coals. However, an increase in pyrolysis temperature caused a gradual increase in quaternary nitrogen as well as a concurrent decrease in pyrrolic nitrogen and a concomitant subtle decrease in pyridinic nitrogen. The analysis of nitrogen in tars was only confined to tars extracted from the FB. Vitrinite-rich and/or high mineral matter coal released high yields of nitrogenous species into the volatile stream at low FB temperatures. A large amount of NH3 was released relative to HCN under FB pyrolysis conditions. However, more HCN was released than NH3 during DTF pyrolysis. Two coals, one characterized by high mineral matter and being rich in vitrinite, and the other distinguished by relatively low mineral matter and being rich in inertinite, behaved similarly by reaching respective peak amounts of NH3 yields at 820 °C under FB pyrolysis conditions. On the contrary, an opposite profile displaying a slump at 820 °C was observed for HCN yields from the two respective coals. The third coal, a high mineral matter and inertinite-rich coal, released high NH3 yields and simultaneously the least HCN yields at 740 °C. Under DTF experimental conditions, both NH3 and HCN steadily increased with temperature in all coals. The low mineral matter and inertinite-rich coal released high yields of total volatile-N from 1000 to 1270 °C, only to be surpassed by the vitrinite-rich/high mineral matter coal at 1400 °C. The inertinite-rich/high mineral matter coal released the least throughout the entire DTF temperature range. The total mineral matter content of the coals played a significant role toward the nitrogen product distribution. On the other hand, the total reactive macerals also influenced the emission of volatile species at 1130–1400 °C DTF temperature range. The yields and composition of the released nitrogenous species have been attributed to a combination of mineral matter content, petrographic properties of the parent coals, and the utilized conditions. Pyrolysis temperature, coal particle size, and residence time also play a significant role toward the yields and composition of the released nitrogenous species.
Chemistry of Alkylaromatics Reconsidered Energy Fuels (IF 3.091) Pub Date : 2018-03-14 Lawrence Lai, Soumya Gudiyella, Mengjie Liu, William H. Green
To investigate upgrading crude oil, alkylaromatic compounds are often chosen as model compounds to better understand their reactivity. In recent kinetic models of this chemistry, the main reaction consuming the alkylaromatic is a four-membered ring “retro-ene” reaction. Here, the transition state of that reaction is discovered to be inconsistent with six-membered ring retroene reactions reported in the literature, leading to inaccurate conclusions. A new detailed kinetic model is constructed using Reaction Mechanism Generator (RMG), and thermodynamic parameters of key compounds and radicals are identified to limit model accuracy. Thermochemistry for key species in the chemistry of hexylbenzene, including hexylbenzene, alkylbenzenes, alkylbenzene radicals, aliphatic radicals, and styrene, was calculated using the CBS-QB3 quantum chemistry method to improve the accuracy of the hexylbenzene pyrolysis model. The kinetics of a key beta scission reaction were also calculated. The results of these calculations have led to an overall improvement in hexylbenzene pyrolysis model predictions.
Higher Ethanodiamondoids in Petroleum Energy Fuels (IF 3.091) Pub Date : 2018-03-14 Guangyou Zhu, Meng Wang, Ying Zhang, Zhiyao Zhang
Higher ethanodiamondoids (ethanodiamantanes and ethanotriamantanes) have been identified for the first time in petroleum. Because ethanodiamondoids are the most thermally stable complex saturated hydrocarbons in petroleum, they appear to reflect the level of oil thermal stress and may serve as a promising reliable indicator for oil cracking and oil maturity. As the ethano-bridged diamond lattice molecules, the extraordinarily thermostable characteristics and predictable derivatizable features of ethanodiamondoids make them attractive components for nanomaterials and devices as well as heat-resistant materials.
Long time, low temperature reactions of Green River oil shale Energy Fuels (IF 3.091) Pub Date : 2018-03-13 Yi Fei, Marc Marshall, W. Roy Jackson, Ying Qi, Anthony Romorosa Auxilio, Alan L. Chaffee, Martin L. Gorbaty, Peter J Cassidy
Reactions of water washed chunks of a deeply buried Green River oil shale (2880-2920 feet, well below the water table) have been carried out in N2-H2O and CO-H2O for up to 28 days at temperatures in the range 280-370oC. Large variations in yields of liquid products were observed for reactions below 330-340oC. These were attributed to varying mineralogy in the chunks, as the variations disappeared for reactions of ground samples or reactions above 330-340oC, where the chunks disintegrated. Liquid product yields of up to 70 wt% dmmf could be obtained from the chunks at temperatures as low as 320oC, provided long reaction times of 14 or 28 days were used. Particularly at lower temperatures, yields were higher under N2 than under CO but the quality of the CO-H2O products tended to be better than that of N2-H2O products. The liquid products contained 1-2 wt% nitrogen, were high in aliphatic material and contained significant amounts of heavily substituted aromatic rings.
Slurrying property and mechanism of coal–coal gasification wastewater–slurry Energy Fuels (IF 3.091) Pub Date : 2018-03-13 Jinqian Wang, Jianzhong Liu, Shuangni Wang, Jun Cheng
The co-slurrying technology of coal and organic wastewater, which achieves the simultaneous disposal and utilization of wastewater, has attracted extensive attention in recent years. The emission of coal gasification wastewater causes serious environmental hazards due to its large amount, high organic content, and high toxicity. In the present study, two types of wastewater, namely, gasifier wastewater (GW) and wastewater from a secondary sedimentation tank (SW), were used to prepare coal water slurry (CWS), which was labeled as coal–GW–slurry (CGS) and coal–SW–slurry (CSS), respectively, with coal–deionized water–slurry (CDS) as reference. The surface property of coal and the dispersing mechanism were characterized using zeta potential and contact angle analyses. Results showed that the fixed viscosity loading decreased with the addition of the two types of wastewater, and the decrease was more considerable with GW. All the slurries exhibited pseudo-plastic behavior and thixotropy, with the following order: CGS > CSS > CDS. Wastewater, particularly GW, strengthened the stability of CWS. The influences of ammonium and volatile phenols on slurry viscosity were also investigated. The effect of ammonium was related to the pH value of the solution. The effect of volatile phenols on the range of wastewater organic content was limited. The stability of CWS was obtained by combining the result of ammonium with organic matter. Ammonium affected the surface charge of coal particles and changed the electrostatic repulsion between coal particles. The amphiphilic organic molecules enhanced the hydrophilicity of coal, which weakened the hydrophobic interaction between particles and thickened the hydration layer. Consequently, the agglomeration of coal particles was weakened.
The ash fusion characteristics and transformation behaviors during bamboo combustion in comparison with straw and poplar Energy Fuels (IF 3.091) Pub Date : 2018-03-13 Youjian Zhu, Junhao Hu, Wei Yang, Wennan Zhang, Kuo Zeng, Haiping Yang, Shenglei Du, Hanping Chen
In this work, the bamboo ash fusion and sintering characteristics were studied to evaluate its potential application in combustion for the production of heat and power. Poplar and wheat straw were used in the experimental test as the reference fuels for comparison. Standard ash fusion tests and ash sintering tests were carried out at elevated temperatures. The results indicate that Bamboo has a low ash melting temperature of 862 °C, much lower than that of poplar. In spite of the high K content in bamboo ash, no severe melting and sintering was observed under the temperature lower than 1000 °C. The ashes after the tests were analyzed using SEM/EDX, XRF and XRD techniques to illustrate the ash transformation behavior. Standard ash fusion tests indicated that the melting temperatures of bamboo, wheat straw and poplar ashes are 862 °C, 770 °C and 1088 °C, respectively. No severe sintering can be observed for poplar due to the large existence of refractory compounds. Ash sintering was occurred when the temperature is higher than 800 °C, for wheat straw, due to the formation of the low melting temperature K-riche silicate. Additionally, bamboo ash has a relatively high P content compared to that of wheat straw, which facilitates the formation of high melting temperature compounds of K-Ca/Mg phosphates. Moreover, the ash content in bamboo is low. As a conclusion, bamboo is a good quality biofuel which can be fired in biomass combustion plants without severe sintering at a temperature lower than 1000 °C.
Separation and Molecular Characterization of Ketones in a Low-Temperature Coal Tar Energy Fuels (IF 3.091) Pub Date : 2018-03-12 Xiu Chen, Chunming Xu, Weilai Zhang, Chao Ma, Xuxia Liu, Suoqi Zhao, Quan Shi
Ketones are major oxygen-containing compounds in low-temperature coal tars (LTCTs); however, the molecular composition of these compounds is not well characterized as a result of the complexity of itself and the interference of the coal tar matrix. In this study, ketones were separated from a LTCT and characterized by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), Orbitrap mass spectrometry (Orbitrap MS), and gas chromatography–mass spectrometry (GC–MS). Isolation of ketones was carried out by a chemical derivatization process with Girard T reagent and followed by a hydrolysis process of the derivatives. The Girard T reagent reacted with ketones under weakly acidic conditions and introduced a charged quaternary ammonium moiety on carbonyl to form water-soluble hydrazones, which can be separated from a complex matrix through an extrography separation and have a strong response in a positive-ion electrospray ionization (ESI) source for mass spectrometric analysis. The isolated derivatives were reversibly turned into the original ketones to selectively separate long alkyl ketones from aromatic ketones with alkyl substituents of C0–C4. The ketones were assigned to 12 class species by high-resolution MS analysis: O1–5 (refers that there are 1–5 oxygen atoms in the molecules), O1S1, N1O1–4, and N2O1–2, among which the O1 class species was the most abundant. The long-chain alkyl ketones, such as aliphatic 2-, 3-, and 4-ketones, alkylcyclopentanones, alkyl phenyl ketones, and aromatic ketones (such as indanone, cyclopentenone, tetralone, acetonaphthone, dihydrophenanthrenone, benzophenone, fluorenone, fluorenyl formaldehyde, anthrone, anthracene formaldehyde, acetylanthracene, acetylphenanthrene, acetylfluorene, benzofluorenone, etc.), were detected by GC–MS. In addition, C18-isoprenoid methyl ketone and tricyclic terpenoids and steroids with one or two oxygen atoms were found in the coal tar.
Multifractal Study of Three-Dimensional Pore Structure of Sand-Conglomerate Reservoir Based on CT Images Energy Fuels (IF 3.091) Pub Date : 2018-03-12 You Zhou, Songtao Wu, Zhiping Li, Rukai Zhu, Shuyun Xie, Cheng Jing, Lei Lei
Sand-conglomerate reservoir has been scarcely studied, and there is no effective method available for quantitative characterization of pore structure of such a reservoir. In this paper, a multifractal study was made on the Triassic Karamay Formation sand-conglomerate reservoir in the Mahu rim region, the Junggar Basin, by using a variety of high-resolution analysis methods, such as Micro-CT, QEMSCAN, and MAPS, in order to quantitatively characterize the heterogeneity of pore size distribution, relative differentiation of large and small pores, and mineral composition. The results reveal that the multifractal parameters have more influence on permeability than on porosity. The smaller the Δα (the multifractal spectral width) and the larger the Δf (the difference in fractal dimension of the maximum and minimum probability subsets), the better the reservoir physical property. To some extent, the relationship between multifractal parameters and mineral composition provides an opportunity to reflect the diagenesis. There is a positive correlation between the clay mineral content and the heterogeneity of the microscopic pore structure of the reservoir. Kaolinite and chlorite cementations are the most significant factors that damage the reservoir pore space. This understanding matches well with the MAPS and QEMSCAN results. With outstanding advantage in quantitatively evaluating the heterogeneity of pore structure of sand-conglomerate reservoir, multifractal theory provides a new idea and method for quantitative characterization of pore structure of other types of heterogeneous oil reservoirs.
Synergism of tert-Heptylated Quaternary Ammonium Salts with Poly(N-vinyl caprolactam) Kinetic Hydrate Inhibitor in High-Pressure and Oil-Based Systems Energy Fuels (IF 3.091) Pub Date : 2018-03-12 Mohamed F. Mady, Malcolm A. Kelland
Quaternary ammonium ionic liquid salts (QAILs) are well known as synergists for kinetic hydrate inhibitor (KHI) polymers such as poly(N-vinyl caprolactam) (PVCap). Earlier work showed that branching of the pentyl tails of tetra(n-pentyl)ammonium bromide to make isohexyl groups and tert-heptyl groups gave a significant improvement in the synergistic KHI performance. We have now evaluated in more detail the KHI performance of tris(tert-heptyl)-N-pentyl-1-ammonium bromide (tris(tert-heptyl)PeAB) or tris(tert-heptyl)-N-propyl-1-ammonium bromide (tris(i-heptyl)PrAB) blended with poly(N-vinyl caprolactam) (PVCap) in steel rocking cells at 130 bar. Due to tris(tert-heptyl)PeAB being sparingly soluble in water we used a water–gas–decane system in order to get this compound dissolved in the fluids. These QAILs were also compared to the known QAILs, tetra(n-butyl)ammonium bromide (TBAB), tetra(n-pentyl)ammonium bromide (TPAB), tetra(n-hexyl)ammonium bromide (TnHexAB), tetra(isohexyl)ammonium bromide (TiHexAB), tetra(n-heptyl)ammonium bromide (TnHepAB), and hexa-n-butylguanidinium chloride (n-Bu6GuanCl),. Under constant cooling test conditions it was found that both tert-heptyl-based QAILs as well as TiHexAB and n-Bu6GuanCl gave particular good synergistic performance results. To further differentiate the ranking of these QAIL synergists, we also conducted long-term isothermal KHI performance tests on the best synergists. When PVCap was mixed with tris(tert-heptyl)PeAB it gave better performance than when mixed with TPAB, TiHexAB, or n-Bu6GuanCl in tests at two different isothermal test conditions. These results highlight the excellent synergy of tert-heptylated quaternary ammonium salts and that sparingly water-soluble but oil-soluble quaternary ammonium salts, with the correct functional groups, can still be good synergists for KHI polymers such as PVCap.
Prediction of Carboxylic and Polyphenolic Chemical Feedstock Quantities in Sweet Sorghum Energy Fuels (IF 3.091) Pub Date : 2018-03-12 Minori Uchimiya, Joseph E. Knoll
The role of minerals in hydrogen sulfide generation during steam assisted recovery of heavy oil. Energy Fuels (IF 3.091) Pub Date : 2018-03-12 Wren Montgomery, Jonathan Watson, James M. Lewis, Huang Zeng, Mark A. Sephton
Heavy oil is recovered from reservoirs using steam-assisted technology, which can lead to H2S generation if the oil is relatively sulfur rich. We have used laboratory aquathermolysis to simulate the steam assisted process and have compared free heavy oil with that contained within the mineral matrix. The presence of a mineral matrix was found to affect the amount of H2S produced and the chemical properties of the oil generated. Our findings show that H2S production is initiated by the presence of naturally occurring minerals at specific temperatures and pressures, and production techniques which avoid these conditions will minimize H2S production.
Dewatering of Oil Sands Tailings with Novel Chitosan-based Flocculants Energy Fuels (IF 3.091) Pub Date : 2018-03-12 Leonardo Pennetta de Oliveira, Sarang Prakash Gumfekar, Fernanda Lopes Motta, Joao B. P. Soares
Mature fine tailings need to be dewatered to reduce the environmental impact caused by oil sands extraction. Polymer flocculants are commonly used to accelerate this process. In this work, we modified chitosan, a naturally occurring biopolymer, with 3-chloro-2-hydroxypropyl trimethylammonium chloride (Chito-CTA), and also grafted polyacrylamide to chitosan (Chito-g-PAM). We compared the dewatering performance of these two flocculants with that of a commercial cationic polyacrylamide (C-PAM). Chito-CTA and Chito-g-PAM dewatered tailings at rates of 18.27 m/h and 20.72 m/h, respectively. The dewatering ability of Chito-CTA and Chito-g-PAM, measured in terms of capillary suction time, was below 10 seconds, whereas the value for C-PAM was 82.3 seconds at optimum dosage. The turbidity of the supernatant obtained after flocculation with Chito-CTA or Chito-g-PAM was below 10 NTU, while C-PAM produced turbid supernatants. We studied the effect of flocculant microstructure on the specific resistance to filtration of the sediments. Chito-g-PAM produced sediments with the lowest resistance, 2.99×1012 m/kg, while C-PAM’s sediments had a much higher resistance of 40.26×1012 m/kg. We also used focussed beam reflectance measurement technique to determine floc size evolution, floc stability, and time required to induce floc formation. Our results indicate that chitosan-based polymers may be successfully used to treat oil sands mature fine tailings.
Evaluation of Accessible Porosity Using Mercury Injection Capillary Pressure Data in Shale Samples Energy Fuels (IF 3.091) Pub Date : 2018-03-12 Davud Davudov, Rouzbeh Ghanbarnezhad Moghanloo, Yuzheng Lan
We present a novel approach to correct accessible/fluid-saturated porosity values calculated using mercury injection capillary pressure (MICP) for shale samples. On the basis of recent studies, accessible porosity of shale samples calculated from the MICP test is corrected to consider conformance and grain compressibility. However, we show here that the shale samples experience an additional phenomenon during the MICP test that has not yet been addressed, i.e., compression of inaccessible/unfilled pores. Therefore, we propose a general approach consisting of three distinct corrections to accurately estimate accessible porosity of the shale sample using MICP data: (1) conformance, (2) grain compressibility, and (3) inaccessible pore compressibility. First, we develop a mathematical model to estimate both pore and grain compressibility using MICP data and then calculate accessible porosity using the above-mentioned corrections. In the mathematical formulation, we divide the shale matrix into three constituents: (1) accessible pores, (2) inaccessible pores, and (3) grains. We, then, estimate volume fractions for each stage using MICP test data. Samples from both Barnett and Haynesville shale plays (11 samples for each shale plays) are used to perform our study and validate the hypothesis. Moreover, the impact of newly proposed corrections on petrophysical properties, such as permeability and pore size distribution, is evaluated. Our results suggest that estimated accessible porosity significantly decreases when new corrections are implemented on the MICP test data. Furthermore, the results suggest that inclusion of correction will shift pore size distribution toward smaller pores and can also dramatically reduce permeability estimations down to 2 orders of magnitude smaller than the original values. The outcome of this study can help determine the fraction of accessible porosity for reserve evaluation purposes in shale plays.
Role of CO2 in the Conversion of Toluene as a Tar Surrogate in a Nonthermal Plasma Dielectric Barrier Discharge Reactor Energy Fuels (IF 3.091) Pub Date : 2018-03-12 Faisal Saleem, Kui Zhang, Adam Harvey
The decomposition of toluene (a model tar compound) in CO2 was investigated at ambient and elevated temperatures in a dielectric barrier discharge (DBD). The effects of reaction parameters, such as the residence time (0.47–4.23 s), plasma power (5–40 W), toluene concentration (20–82 g/Nm3), and temperature (20–400 °C), were investigated. The DBD was shown to be an effective technique for tar removal. The percentage removal of tar increased with increasing the plasma power and residence time (to as high as 99% at the residence time of 4.23 s). The maximum selectivity to the two major gaseous products, CO and H2, was 73.5 and 21.9%, respectively. Solid residue formation was also observed inside the reactor. The synergetic effect of the temperature and plasma power was studied. As temperature increased, the decomposition of toluene decreased slightly from 99 to 88% (from ambient to 400 °C at 40 W) and the selectivity of CO and H2 decreased as a result of the increased rate of recombination of CO and O. The selectivity to lower hydrocarbons increased with the temperature.
CO2 Gasification of Municipal Solid Waste in a Drop-Tube Reactor: Experimental Study and Thermodynamic Analysis of Syngas Energy Fuels (IF 3.091) Pub Date : 2018-03-12 Xiaoyuan Zheng, Zhi Ying, Bo Wang, Chong Chen
A gasification-based waste-to-energy technique has been considered as a promising alternative to direct incineration. With the potential benefits of reducing the greenhouse gas emission and producing syngas, CO2 gaisification of municipal solid waste (MSW) was studied in a drop-tube reactor. Process parameters, including the temperature and CO2/MSW mass ratio, were investigated. On the basis of the experimental results, energy and exergy analyses were conducted to evaluate the thermodynamic quality. Results indicated that the temperature had a significant impact on the syngas composition, while the effects of the CO2/MSW mass ratio were not so profound. The tendency of the syngas composition revealed that the Boudouard reaction, water gas reaction, and free radical combination reaction were the most influential reactions in the gasification process. Energy and exergy analyses showed that the total energy and exergy values of syngas increased with the rising temperature, whereas they declined initially and then rose with the increase in the CO2/MSW mass ratio. The detailed energy and exergy distributions of the syngas component were different at various temperatures and CO2/MSW mass ratios. As a result of the remarkable difference between physical energy and exergy of sensible heat, the exergy value of syngas was much lower than its energy value. It followed well with the energy value.
Effects of Dissolved Oxygen on Water Imbibition in Gas Shales Energy Fuels (IF 3.091) Pub Date : 2018-03-12 Mingxiang Xu, Mojtaba Binazadeh, Ashkan Zolfaghari, Hassan Dehghanpour
Understanding the water uptake of gas shales is critical for designing and optimizing hydraulic fracturing operations during which a large volume of fracturing water containing dissolved oxygen is injected into tight reservoirs. Recent studies show that the dissolved oxygen may promote oxidation reactions which can affect salinity and pH value of flowback water; however, the effects of dissolved oxygen and oxidation reactions on water imbibition into the shale matrix and on the concentration of individual ions in flowback water are still poorly understood. In this study, we conduct water imbibition experiments under degassed and oxic conditions, and measure the imbibed water volume and concentrations of different ions in water. The results show that the initial rate and final amount of water imbibition are higher under degassed conditions compared with that under oxic conditions. These differences are mainly due to the enhanced dissolution of air in the shale pore network into the imbibing water under degassed conditions and the consequent increase in relative permeability of water. The results also suggest that oxidation of pyrite by dissolved oxygen produces sulfate and iron ions, as well as iron-compound precipitations. Pyrite oxidation is also supported by the abundance of pores in the vicinity of pyrite minerals observed in the SEM/EDS images.
Evaluating the Thermal Extrusion Behavior of a Coking Coal for Direct Carbon Fiber Production Energy Fuels (IF 3.091) Pub Date : 2018-03-09 Rohan Stanger, Quang Anh Tran, Mariah Browne, John Lucas, Minoo Naebe, Murray Height, Terry Wall
This study outlines a novel thermal extrusion system and methodologies for evaluating the potential to manufacture carbon fiber directly from thermoplastic coals. It is envisioned that the intermediate product will be further refined by spinning down to commercial fiber sizes and thermal annealing. Commercial melt spinning is used for manufacturing carbon fibers from pitch-based feed materials, and a similar approach for plasticized coal is likely to be a lower risk option. However, the critical aspect of using coal for this purpose is its behavior inside a higher pressure extrusion unit and the need to characterize its rheology. This work has evaluated the thermoplastic development needed for extrusion of a single coking coal in terms of the heating rate and residence time and characterized the extruded fiber product. It was observed that the coal underwent a preliminary softening phase prior to extruding at significant speed. This phase appeared necessary to develop the critical viscosity for extrusion and was affected by the heating rate. The size of the orifice that the coal was extruded through also impacted the point of extrusion, with the smaller 0.5 mm hole requiring lower viscosity to be developed to flow at steady state. Other operating modes were developed to examine the thermoplastic properties of the coal over an extended residence time, and it was found that the coal could be maintained up to 60 min at selected temperatures. The product fiber was larger than the commercial size, appearing slightly larger than the orifice size. Internal porosity and surface roughness were observed as coal-based fiber qualities in need of controlling, along with the mineral content and size.
High-Accuracy, Temperature Dependent Density and Viscosity Measurements of a 50/50 JP-10 + Terpene Mixture Energy Fuels (IF 3.091) Pub Date : 2018-03-09 Stephanie L. Outcalt, Tara J. Fortin
Densities of a 50/50 by volume mixture of JP-10 + a turpentine dimer fuel (TDF) have been measured in the compressed-liquid state from 270 to 470 K and at 0.5–45 MPa and at ambient pressure from 263.15 to 373.15 K. Ambient-pressure dynamic viscosity has also been measured over the same temperature range. The density data have been correlated with a Rackett equation, and the compressed-liquid density data have been fit to a Tait equation. Correlation parameters are given. Results of the mixture measurements presented here are compared with previously measured densities of the individual components, TDF and JP-10. Measurements of density over large ranges of temperature and pressure, as well as viscosity measurements, provide information as to the suitability of a fuel for use as a drop-in replacement for traditional petroleum-based fuels. The large range in temperature and pressure of the measurements is important to more closely capture engine operating conditions and better access the potential of alternative fuel candidates.
Producing Aromatic-Enriched Oil from Mixed Plastics Using Activated Biochar as Catalyst Energy Fuels (IF 3.091) Pub Date : 2018-03-09 Kai Sun, Qunxing Huang, Mujahid Ali, Yong Chi, Jianhua Yan
Producing aromatic-enriched oil from mixed plastics through catalytic pyrolysis has been experimentally studied. The effect of biochar catalysts has been investigated, and the possible dominating catalytic mechanisms of biochars activated with different chemical agents have been discussed. Results indicated that when waste plastics were pyrolyzed with raw biochar, the alkene fraction in the oil product increased to 54.9%. When biochar was activated by ZnCl2, KOH, and H3PO4, the oil product showed high selectively toward aromatics, and the proportions of aromatics were up to 47.6, 44.7, and 66.0%, respectively. Benzene, 1,1′-(1,3-propanediyl) bis- was the main composition in aromatics, the proportion of which could be up to 25.1% when KOH-activated biochar was used. The enrichment part of aromatics was mainly bicyclic aromatics and C15–C16 compositions, the maximum proportions of which could reach 92.5 and 28.1% by KOH-activated biochar. High surface functional group (e.g., C═O) content and low metal content of KOH-activated biochar promoted hydrogen transfer reaction of alkenes to alkanes and aromatics, whereas the aromatization process promoted by Lewis acid sites and Brønsted acid sites on ZnCl2- and H3PO4-activated biochar, respectively, significantly increased aromatic yield.
Preparation and Characterization of Modified Porous Wood Flour/Lauric-Myristic Acid Eutectic Mixture as a Form-Stable Phase Change Material Energy Fuels (IF 3.091) Pub Date : 2018-03-09 Liyun Ma, Chuigen Guo, Rongxian Ou, Lichao Sun, Qingwen Wang, Liping Li
In this research, porous wood flour (WF) and a eutectic mixture of lauric acid (LA) and myristic acid (MA) were prepared as a form-stable phase change material (FSPCM) using a vacuum impregnation method. The effects of alkali (NaOH), cetyltrimethylammonium bromide, and complex salts (CS) on the pore size of the WF were investigated. The results showed that the CS-treated WF (CS-WF) achieved the maximum pore size and impregnation ratio. The characterization by Fourier-transform infrared spectrometer, X-ray photoelectron spectrometer, and X-ray diffractometer illustrated that the combination of the LA-MA eutectic mixture and the CS-WF was a physical combination. The differential scanning calorimetry results suggested that the optimum melting temperature and the latent heat of the CS-WF/LA-MA FSPCM were 33.1 °C and 98.2 kJ kg–1, respectively. The maximum impregnation ratio of the LA-MA eutectic mixture into the CS-WF was 60.3%. In addition, the thermogravimetric analysis indicated that the CS-WF/LA-MA FSPCM had better thermal durability than the pure LA-MA. Moreover, the CS-WF/LA-MA FSPCM had excellent thermal reliability after 500 thermal cycles. Thus, the CS-treatment of the WF was considered an excellent modification method. The prepared CS-WF/LA-MA FSPCM has the potential for latent heat thermal energy storage applications in terms of the proper phase-transition properties.
Removal of NOx from Flue Gas Using Yellow Phosphorus and Phosphate Slurry as Adsorbent Energy Fuels (IF 3.091) Pub Date : 2018-03-09 Shuai Li, Jiaqiang Yang, Chi Wang, Delong Xie, Yongming Luo, Kai Li, Dedong He, Yi Mei
Downhole Kinetics of Reactions Involving Alcohol-Based Hydraulic Fracturing Additives with Implications in Delayed H2S Production Energy Fuels (IF 3.091) Pub Date : 2018-03-09 Juan J. Marrugo-Hernandez, Rohen Prinsloo, Saud Sunba, Robert A. Marriott
Influence of Fatty-Alkylamine Amphiphile on the Asphaltene Adsorption/Deposition at the Solid/Liquid Interface under Precipitating Conditions Energy Fuels (IF 3.091) Pub Date : 2018-03-09 Sreedhar Subramanian, Lola Buscetti, Sébastien Simon, Marion Sacré, Johan Sjöblom
The ability of a fatty-alkylamine amphiphile to inhibit asphaltene adsorption/deposition, as well as its ability to disperse the asphaltene layers on stainless steel, was studied using a quartz crystal microbalance with dissipation (QCM-D). The experiments were performed both under good solvent conditions and above asphaltene precipitation onset. The adsorption/deposition of asphaltenes from model oil solution in xylene/n-hexane was found to strongly increase up to the asphaltene precipitation onset (i.e., ∼60–65 vol % n-hexane), with a 7–8 times increase of the adsorbed amount, compared with adsorption from xylene. Beyond the precipitation onset, the amount of asphaltene adsorbed/deposited decreases. Under both good solvent and precipitating conditions, the amphiphile was unable to form a protective layer on stainless steel to prevent asphaltene adsorption/deposition. However, the amphiphile exhibited an excellent ability to reduce asphaltene adsorption/deposition by 80–95 wt % when injected along with asphaltene solution. It is found that the interactions between asphaltenes and inhibitor that are responsible for the adsorption/deposition inhibitory action are not of an acid–base nature. Maximum inhibitory action in minimizing the asphaltene adsorption/deposition was observed corresponding to a molar ratio (amphiphile/asphaltenes) of ∼0.10, despite this molar ratio being insufficient to prevent asphaltene precipitation. Similarly, the amphiphile also displayed an ability to remove 90–95 wt % of asphaltenes already adsorbed/deposited on stainless steel under precipitating conditions, thereby showing its effectiveness as both an asphaltene inhibitor (AI) and an asphaltene dispersant (AD) under good solvent conditions, as well as precipitating conditions.
Integrated Dynamic and Steady State Method and Its Application on the Screening of MoS2 Nanosheet-Containing Adsorbents for Hg0 Capture Energy Fuels (IF 3.091) Pub Date : 2018-03-09 Haitao Zhao, Hua Fan, Gang Yang, Lu Lu, Chenghang Zheng, Xiang Gao, Tao Wu
In this research, an integrated dynamic and steady state (IDSS) method was developed to accelerate the discovery of new materials for the capture of Hg0, a pollutant that is associated with fossil fuel utilization and has significant impacts on health and the ecosystem. A suite of metal sulfides and MoS2-based binary metal sulfides were evaluated using this method. It was found that the existence of MoS2 nanosheets promoted the Hg0 removal efficiency of these metal sulfides. Among the MoS2-based metal sulfides studied in this research, Co–Mo–S and Cu–Mo–S exhibited excellent performance with an almost complete removal of Hg0 at low temperatures. The results are superior to their corresponding metal oxides and the MoS2-containing adsorbent and are comparable to that of the commercial carbon-based adsorbent. Moreover, the working temperature windows for Hg0 capture were found to be broader for the Mo-based binary metal sulfides than the corresponding metal oxides. The Co–Mo–S and Cu–Mo–S also showed better performance on Hg0 capture than other samples. It is proved that the IDSS approach is an effective and efficient method for the rapid screening of adsorbents for Hg0 capture, which could be applied in the development of adsorption materials for environmental applications.
Synthesis and Application of Amphiphilic Poly(ionic liquid) Dendron from Cashew Nut Shell Oil as a Green Oilfield Chemical for Heavy Petroleum Crude Oil Emulsion Energy Fuels (IF 3.091) Pub Date : 2018-03-09 Ayman M. Atta, Mahmood M. S. Abdullah, Hamad A. Al-Lohedan, Amany K. Gaffer
Experimental Study on Aquathermolysis of Different Viscosity Heavy Oil with Superheated Steam Energy Fuels (IF 3.091) Pub Date : 2018-03-09 Shijun Huang, Meng Cao, Linsong Cheng
In this work, a large number of experiments have been carried out to study the aquathermolysis of heavy oil of different viscosities with superheated steam. First, a high-temperature and high-pressure autoclave was independently designed to carry out an aquathermolysis reaction with superheated steam. Second, the viscosities of the heavy oil samples were measured before and after the aquathermolysis reaction by an MCR 302 rheometer. Finally, both the saturates, aromatics, resins, and asphaltenes (SARA) content and the carbon number distribution of heavy oil samples before and after the aquathermolysis reaction were determined by chromatography. The experimental results show the following: (1) The higher the content of resins and asphaltenes, the longer is the reaction time for aquathermolysis equilibrium. (2) As for different viscosity oil samples, the starting temperature for aquathermolysis is different; however, the reaction temperature for aquathermolysis equilibrium is the same. (3) The cracking of resins is the main mechanism for the aquathermolysis of low-viscosity heavy oil. The cracking of resins is also the dominant mechanism for the aquathermolysis of medium-viscosity heavy oil, accompanied by the cracking of asphaltenes. The cracking of resins and asphaltenes is the primary mechanism for the aquathermolysis of high-viscosity heavy oil. (4) The cracking of long-chain hydrocarbons into short-chain hydrocarbons is the main mechanism of aquathermolysis.
Ethanol Production from Brewers’ Spent Grain Pretreated by Dilute Phosphoric Acid Energy Fuels (IF 3.091) Pub Date : 2018-03-09 José A. Rojas-Chamorro, Cristóbal Cara, Inmaculada Romero, Encarnación Ruiz, Juan M. Romero-García, Solange I. Mussatto, Eulogio Castro
This paper deals with the characterization of brewer’s spent grain (BSG) and the optimization of the phosphoric acid pretreatment for this feedstock. The influence of temperature and acid concentration on BSG was studied, and the optimal conditions were found to be 155 °C and 2% H3PO4. The use of both pretreatment and enzymatic hydrolysis together recovered 92% of total sugars in BSG, mainly solubilized in the prehydrolysate (63%). Escherichia coli SL100 fermented this mixed sugar solution containing hemicellulosic sugars and starchy glucose without previous detoxification with an ethanol yield of 0.40 g/g. Considering also the glucose released from the cellulosic structure and converted to ethanol by a simultaneous saccharification and fermentation process, an overall ethanol yield of 17.9 g of ethanol per 100 g of raw BSG was achieved. Thereby, the process configuration proposed in this work allowed 69% of the total sugars in the BSG to be converted to ethanol.
What Differences Does Large Eddy Simulation Find among Traditional, High-Temperature, and Moderate or Intense Low Oxygen Dilution Combustion Processes of a CH4/H2 Jet Flame in Hot Oxidizer Coflow? Energy Fuels (IF 3.091) Pub Date : 2018-03-08 Guochang Wang, Jianchun Mi
Large eddy simulation (LES) of a CH4/H2 diffusion jet flame in hot coflow (JHC) is undertaken to find distinct behaviors of moderate or intense low oxygen dilution (MILD) combustion (MILDC), high temperature combustion (HTC), and traditional combustion (TC). These three JHC flames are realized by using different coflow temperatures and oxygen mass fractions: (1) 1300 K and 9% for MILDC; (2) 1300 K and 30% for HTC; (3) 600 K and 30% for TC. The modeling of LES combining the eddy dissipation concept (EDC) with a global four-step reaction mechanism is validated by the JHC measurements of Dally et al. (Proc. Combust. Inst. 2002, 29, 1147–1154). The instantaneous and time-averaged velocities, temperatures, and species concentrations such as carbon monoxide (CO) are presented and compared for the three cases. It is demonstrated that the JHC flames of MILDC and HTC both develop from autoignition nearly immediately downstream of the nozzle exit, while the lift-off JHC flame of TC evolves from an induced-ignition with a significant delay. Manifestly, combustion reactions proceed gently in the MILDC case and highly aggressively in the TC case. In both MILDC and HTC cases, stable combustion ensues in the very near field. While most heat releases around the stoichiometric location and transfers away slowly, combustion species, for example, CO, diffuse more rapidly across the jet flow. The JHC flame for TC behaves completely differently. With a wobbling flame base, large-scale flame oscillations enhance crosswise turbulent mixing and heat transfer. Consequently, high temperatures and high CO concentrations concurrently emerge across the central region in the mid field. Besides, local extinction and reignition appear to occur frequently in the TC and do not happen in the HTC and MILDC.
Role of Bubble–Drop Interactions and Salt Addition in Flotation Performance Energy Fuels (IF 3.091) Pub Date : 2018-03-08 H. Chakibi, I. Hénaut, A. Salonen, D. Langevin, J.-F. Argillier
Gas flotation is an efficient technique used in the petroleum industry to remove oil contamination from produced water. This method is based on attaching air bubbles to oil droplets to make oil droplets rise faster. We investigated the role of water salinity in the efficiency of the process, using a model flotation column. We show that flotation efficiency increases with water salinity, highlighting the importance of the electrostatic repulsion between oil drops and air bubbles. We also studied the attachment between drops and bubbles, monitoring the temporal evolution of the thin films between them. Stable attachment requires that the water films formed between oil drops and air bubbles break and the oil spreads at the bubble surface. Increasing the salinity of the solution decreases the repulsion between the oil drops and the air bubbles, which in turn decreases the water film stability. The films rupture more readily, improving the drop–bubble attachment and thus the flotation efficiency. The differences in water salinity can therefore lead to important changes in the flotation efficiency.
Effects of Temperature and Equivalence Ratio on Carbon Nanotubes and Hydrogen Production from Waste Plastic Gasification in Fluidized Bed Energy Fuels (IF 3.091) Pub Date : 2018-03-08 Ren-Xuan Yang, Kui-Hao Chuang, Ming-Yen Wey
The waste plastic gasification in a fluidized bed for a continuous carbon nanotube (CNT) and hydrogen coproduction is a potential method for sustainable management. Ni/Al2O3 catalysts have been synthesized by the impregnation method to upgrade hydrogen production and CNT synthesis. However, few studies investigated the effect of operating parameters for upcycling waste plastics into CNTs and hydrogen in the fluidized-bed system. The reaction temperature and the equivalence ratio (ER) were evaluated for CNT and hydrogen coproduction. Increasing the reaction temperature and lowering the ER enhanced the methane dry reforming, hydrocarbon dry reforming, and hydrocarbon direct decomposition for hydrogen and CNT coproduction. While increasing the reaction temperature from 500 to 700 °C can obtain higher CNT yield and H2 production rate, the system heated to 700 °C and maintained at this temperature should provide more energy. Moreover, the gas composition at 600 °C with 0.1 ER contained more CH4 and C2–C5 hydrocarbons compared with that with a higher ER, which could be used as the carbon source of CNTs. The reaction temperature of the fluidized bed in the waste plastic gasification system controlled at 600 °C with 0.1 ER and the gasified products upgraded through a catalytic fixed-bed reactor at 680 °C exhibited an optimal catalytic performance of less-defective CNTs in 22.0% yield and H2 production rate (385.1 mmol/h-g catalyst).
SO3 Removal from Flue Gas with Ca(OH)2 in Entrained Flow Reactors Energy Fuels (IF 3.091) Pub Date : 2018-03-08 Hui Wang, Denggao Chen, Zhenshan Li, Dinghai Zhang, Ningsheng Cai, Jin Yang, Geng Wei
Experiments were carried out in a pilot-scale entrained flow reactor (EFR) to investigate the reaction of SO3 with Ca(OH)2 as a method of dry sorbent injection (DSI) for SO3 removal from flue gas. The results indicate that SO3 can be removed by Ca(OH)2 with an efficiency that can reach 80%, and it was found that the molar ratio of Ca(OH)2 to SO3 ([Ca]/[S]) and reaction temperature have a significant effect on SO3 removal efficiency. The experimental data measured inside the EFR were analyzed with a computing fluid dynamic (CFD) simulation, in which the Euler–Lagrangian frames were used for gas- and discrete-phase modeling. The CFD models were validated and applied to analyze the effects of certain parameters on SO3 removal efficiency, such as particle velocity, [Ca]/[S], temperature and residence time. It was found that the sorbent diameter has a significant influence on SO3 removal efficiency, with an obvious decrease in efficiency if the Ca(OH)2 particle diameter increases. For example, if the sorbent diameter increases from 3 to 10 μm, the SO3 removal efficiency at the reactor outlet will decrease from 99% to 55%. A detailed comparison and theoretical analysis indicated that external diffusion of SO3 from the gas phase to the particle surface is the rate controlling step for larger Ca(OH)2 particles, and more attention should be paid to the competition between external diffusion and surface reaction when applying the DSI method for removing SO3 from flue gas.
Process Modeling of a Biomass Torrefaction Plant Energy Fuels (IF 3.091) Pub Date : 2018-03-08 Yousef Haseli
A process model is developed to simulate the performance of a biomass torrefaction unit, which consists of a dryer, a torrefaction reactor, a combustor, and two heat exchangers. The model is capable of predicting the composition of volatiles and torrefied biomass, mass and energy yields, thermal efficiency, process heat requirement, and CO2 emissions. Useful correlations are presented for the heating value, molecular weight, and specific heat of the volatiles. A comparison of the model prediction with the experimental data reported in the literature showed a very good agreement. The effect of moisture content, torrefaction temperature, residence time and adiabatic flame temperature on key process parameters are examined. The thermal efficiency is found to be 88% at a moisture content of 50% (dry basis), which increases to 94% as the moisture content drops to 20%. The results show that the carbon dioxide produced in the process is notably affected by the torrefaction temperature and the moisture content. A higher moisture content or torrefaction temperature may lead to a higher CO2 emission. Furthermore, the conditions at autothermal operation are identified and discussed.
Reducing VOC off-gassing during the production of pelletized steam-exploded bark: Impact of storage time and controlled ventilation Energy Fuels (IF 3.091) Pub Date : 2018-03-08 Eleonora Borén, Sylvia Helena Larsson, Andreas Averheim, Mikael Thyrel, Markus Broström
Volatile organic component (VOC) off-gassing behavior of thermally treated biomass intended for bioenergy production has recently been shown to be vastly different from that of untreated biomass. Simple measures to reduce emissions, such as controlled ventilation and prolonged storage time, have been suggested but not yet studied in detail. In the present study, we monitored how VOC off-gassing was reduced over time (24 h–144 h) in enclosed storage with and without ventilation. Steam-exploded bark was collected directly from a pilot-scale steam explosion plant, as well as before and after subsequent pelletizing. Active Tenax-TA absorbent sampling of VOCs was done from the headspaces of a bench-scale sample storage set-up. The impact of storage time and ventilation on VOC levels was evaluated through multivariate statistical analysis. The results showed that relative VOC concentrations in the headspace were reduced by increased storage time, with heavier VOCs reduced at a higher rate. VOC composition was neither reduced nor shifted by controlled intermittent ventilation during storage; instead, VOC levels equilibrated at the same levels as those stored without ventilation, and this was independent of process step, storage time, or number of ventilations.
Partial Upgrading of Bitumen by Thermal Conversion at 150–300 °C Energy Fuels (IF 3.091) Pub Date : 2018-03-08 Lina Maria Yañez Jaramillo, Arno de Klerk
Bitumen produced from oilsands deposits has a high viscosity, which presents a challenge to pipeline transport. Ways to reduce the viscosity at low incremental production cost are desirable. Thermal conversion of oilsands-derived bitumen at temperatures in the range of 150–300 °C was explored as a potential strategy for viscosity reduction. Viscosity increased compared to the bitumen feed following thermal treatment of bitumen at 150 and 200 °C but decreased following thermal treatment at 250 and 300 °C. At all temperatures studied, changes in the chemical and physical nature of the product were observed within 1 h of reaction time, and changes continued as reaction time was extended to a period of 8 h. Hydrogen transfer and methyl transfer were important reactions. These transfer reactions appeared to be concerted in nature and did not involve cracking to release free hydrogen or methyl radicals. In fact, thermal cracking was a minor reaction. The olefin content of the liquid was low, there was little gas-make, and the H2S concentration in the gaseous product was low. The n-pentane insoluble (asphaltenes) content of the liquid, with a few exceptions, increased during thermal conversion, but it was poorly correlated to viscosity. It is unlikely that the change in viscosity can be attributed to a single factor. The two most important factors appeared to be (i) the formation of heavier molecules that caused an increase in “excluded volume” with a concomitant increase in viscosity and slight decrease in density and (ii) a change in the phase behavior of the product due to chemical changes in the product.
Integrated Supercritical Fluid Extraction and Fluid Thermal Conversion Process: Experiment Realization and Comparison of Thermal Converted Liquids Energy Fuels (IF 3.091) Pub Date : 2018-03-08 Haipeng Song, Zhiming Xu, Xuewen Sun, Linzhou Zhang, Chunming Xu, Suoqi Zhao, He Huang
A new technology is proposed by the directly integrated supercritical fluid extraction and fluidized thermal conversion process, which was named the integrated supercritical fluid extraction and fluid thermal conversion (ISFTC) process. In the extraction unit of ISFTC, the heavy feedstock was separated into deoiled asphalt (DOA) and deasphalted oil (DAO). The DOA phase is fed to a fluidized-bed thermal convertor (FTC) without solvent separating, using hot coke to supply the heat. DAO will be qualified for fluid catalytic cracking (FCC) processing. The proposed process avoids the feedstock quality limit for both FCC and delayed coking (DC). It increased the overall liquid yield of vacuum residue (VR) upgrading and solved the problem of solvent recovery for the solvent–DOA phase at the bottom of the supercritical fluid extraction unit. A continuous laboratory apparatus was built to prove the concept. A Chinese petroleum residue was processed by the built apparatus at appropriate operating conditions. The total liquid yield of ISFTC, the DAO FCC liquid plus DOA FTC liquid, is 7 and 14 wt % higher than VR DC and VR FTC, respectively. The bulk properties, such as the molecular weight, carbon residue, density, viscosity, and elemental contents, of DOA converted liquid were compared to those of VR DC and VR FTC. The structure parameters based on 1H nuclear magnetic resonance were also calculated. To investigate the molecular composition difference of acidic, non-basic, and basic heteroatom species in three samples, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was applied with negative- and positive-ion electrospray ionization (±ESI) as ion sources. The quality and compositions of DOA FTC liquid are similar to VR FTC liquid but worse than VR DC.
Numerical Investigation of Supercritical Combustion of H2–O2 Energy Fuels (IF 3.091) Pub Date : 2018-03-07 A. Mardani, E. Barani
This study investigates GH2/LOX coaxial jet flame at trans- and supercritical conditions using the Reynolds averaged Navier–Stokes approach. Four two-equation-turbulence models, three real equation of states, two chemical mechanisms, and three different chamber pressures are examined. Predictions show good agreement with measurements qualitatively and quantitatively. Based on the results, the predictions of the Soave–Redlich–Kwong equation of state (EOS) are closer to the experiment, while the Aungier–Redlich–Kwong EOS has more deviation than the others. Moreover, the k–ω shear stress transport model has better performance than the other turbulence models. It is also found that the flow field is controlled by two vortices which resulted from extreme expansion of the oxygen dense core and high velocity of inlet gaseous hydrogen into the chamber. The chamber pressure increment delays transcritical conditions and also increases flame length and the length of the secondary vortex and decreases the expansion zone. Furthermore, the two detailed chemical mechanisms of Burke and Konnov had a similar result.
Slow Pyrolysis Performance and Energy Balance of Corn Stover in Continuous Pyrolysis-Based Poly-Generation Systems Energy Fuels (IF 3.091) Pub Date : 2018-03-07 Hongbin Cong, Ondřej Mašek, Lixin Zhao, Zonglu Yao, Haipo Meng, Erfeng Hu, Teng Ma
In order to analyze pyrolysis performance and energy balance of corn stover pyrolysis, a poly-generation pyrolysis unit that coproduced biochar, pyrolysis gas, and liquids was used. Corn stover was naturally dried and crushed to lengths of 4–7 mm before pyrolysis at 450, 550, and 650 °C. The physical and chemical properties, yield rate, and influence of technological parameters were analyzed. In addition, a full energy balance analysis was carried out. The results show that the quality of corn stover char was primarily affected by pyrolysis temperature and material residence time, where a residence time of at least 30 min was required for conversion in this unit. The higher heating value (HHV) of pyrolysis gases reached ∼20 MJ/Nm3 at pyrolysis temperatures of 550 and 650 °C, providing a useful gaseous fuel. In terms of energy balance, biochar contributing 47.88% accounted for most of the enthalpy of products, followed by pyrolysis gas (36.17%), wood tar (13.14%), and light oil (1.74%), and the last fraction, wood vinegar, accounted for only ∼1.07% of the total product enthalpy. The theoretical energy efficiency of the poly-generation system was 82.1%. Pyrolysis at temperatures of 550 and 650 °C could provide fuel gases that contained enough energy to support the heating requirements of the system. The researcher offers an important new direction for comprehensive development of straw utilization for energy and materials, not only in China, but worldwide.
Solubility and Nucleation of Methyl Stearate as a Function of Crystallization Environment Energy Fuels (IF 3.091) Pub Date : 2018-03-07 Diana M. Camacho, Kevin J. Roberts, Iain More, Ken Lewtas
Crystallization studies of methyl stearate from supersaturated dodecane, kerosene, and toluene solutions reveal strong evidence that solvent choice influences solubility and nucleation behavior. Solute solubility is less than ideal with toluene, kerosene, and dodecane, respectively, exhibiting the closest behavior to ideality, the latter consistent with the highest solvation. Polythermal crystallization studies using the Kashchiev–Borissova–Hammond–Roberts (KBHR) model [Kashchiev et al. J. Phys. Chem. B 2010, 114, 5441; Kashchiev et al. J. Cryst. Growth 2010, 312, 698; Camacho et al. CrystEngComm 2014, 16, 974] reveal a progressive nucleation (PN) mechanism with crystallite interfacial tension (γeff) values between 0.94 and 1.55 mJ/m2, between 1.21 and 1.91 mJ/m2, and between 1.18 and 1.88 mJ/m2 for dodecane, kerosene, and toluene, respectively. Nucleation rates at the critical undercooling lie between 4.56 × 1016 and 1.79 × 1017 nuclei/mL·s, with the highest rates associated with crystallization from kerosene solutions. Iso-supersaturation nucleation rates are the highest for dodecane ranging from 2.39 × 1017 to 3.63 × 1018 nuclei/mL·s. Nucleation in toluene appears to be hindered by its relatively higher interfacial tension, which is associated with nucleation rates about an order of magnitude less than those obtained for dodecane.
Investigation of Pore Characteristics and Irreducible Water Saturation of Tight Reservoir Using Experimental and Theoretical Methods Energy Fuels (IF 3.091) Pub Date : 2018-03-07 Fengpeng Lai, Zhiping Li, Wei Zhang, Hongkui Dong, Fanshuai Kong, Zhiyu Jiang
Characterizing pore structure is one of the most fundamental tasks in reservoir characterization; it is closely related to the calculation/interpretation of other critical parameters, such as permeability and capillary pressure. High-pressure mercury injection (HPMI), a low-pressure nitrogen gas adsorption (LP-N2GA), specific surface area (SSA) analysis, nuclear magnetic resonance (NMR), and fractal theory were used to study the pore structure characteristics and irreducible water saturation of tight reservoir samples from the Chang 7 formation in Ordos Basin, China. In this study, pores are mainly composed of mesopores and macropores. HPMI is more likely to detect macropores, while the distribution of mesopores is better characterized by LP-N2GA and SSA analysis. The capillary curves obtained by HPMI experiments are divided into two categories. The adsorption–desorption isotherms are divided into two groups, according to the rate of change of the desorption curve when the relative pressure is 0.5. The permeability contribution rate of different pore radius was studied through different methods, and the results showed the combination of HPMI and LP-N2GA can describe the microscopic pore structure of a reservoir more comprehensively than either method alone. The irreducible water saturation obtained by NMR test is greater than the irreducible water saturation obtained by HPMI. An irreducible water saturation model was established based on fractal theory and the capillary bundle model. The factors affecting the irreducible water saturation were fractal dimension, maximum connected pore throat radius, minimum pore throat radius, and thickness of the water film. The calculation results are closer to the experimental value when the fractal dimension is greater than 2.7. This comprehensive application of various experimental and theoretical methods gives a better understanding of the pore structure characteristics and fluid distribution in tight reservoir samples.
Wax Deposition Experiment with Highly Paraffinic Crude Oil in Laminar Single-Phase Flow Unpredictable by Molecular Diffusion Mechanism Energy Fuels (IF 3.091) Pub Date : 2018-03-07 Charlie Van Der Geest, Vanessa C. Bizotto Guersoni, Daniel Merino-Garcia, Antonio Carlos Bannwart
Wax deposition data for a Brazilian crude oil was investigated using a facility designed to study flow assurance problems related to waxy crude oils. This work reports the preliminary efforts behind validating the pressure drop methods in place for identifying deposition, i.e., isothermal and nonisothermal flows were evaluated, to confirm whether it was possible to differentiate between temperature gradient effects, and wax deposition. Additionally, deposition experiments show a phenomenon that is not commonly reported in the literature. Once the oil’s temperature was below the wax appearance temperature and the water temperature at 5 °C, the deposit did not start to build up immediately; it only began after a period of time. Under some conditions the pressure drop only began increasing after 1 day. These results show that, at least for highly paraffinic crudes, models based on molecular diffusion alone cannot predict when and where the deposit will form, which is a major concern in the industry. We believe that other mechanisms such as shear dispersion, Brownian diffusion, and the non-Newtonian behavior of waxy crudes at low temperatures should be considered. In this experimental setup two different ways were used to measure deposit thickness: (1) pressure drop and (2) weight of the deposit.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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