Reduced Chemical Kinetic Mechanism for a Waste Cooking Oil Biodiesel/n-Pentanol Mixture for Internal Combustion Engine Simulation Energy Fuels (IF 3.024) Pub Date : 2018-12-10 C. V. Manojkumar, Justin Jacob Thomas, V. R. Sabu, G. Nagarajan
With increasing pollution concerns and stringent emission regulations, it has become difficult to meet the emission standards with the use of a single fuel. Binary and ternary fuel mixtures are being investigated all over the globe to satisfy the emission norms. In the present work, a reduced reaction mechanism for a waste cooking oil (WCO) biodiesel/n-pentanol mixture is proposed for the chemical kinetic simulation of an internal combustion engine. The mechanism consists of 146 species and 506 reactions. WCO biodiesel and n-pentanol are biofuels with many advantages. WCO biodiesel has properties (cetane number, viscosity, etc.) that are similar to those of diesel fuel, whereas n-pentanol has a high boiling temperature, low heat of vaporization, high lower heating value, and low autoignition temperature compared to other shorter chain alcohols. Mixing of higher molecular weight alcohols (n-pentanol) with diesel/biodiesel lowers the knock resistance as a result of their high reactivity at low as well as high temperatures. This characteristic makes them suitable for a diesel engine and advanced engine combustion modes, such as homogeneous charge compression ignition and reactivity controlled compression ignition engines.
Removal of Organic Sulfur in Hydrocarbon Liquid Model Fuel by Ni-Loaded Carbon Prepared from Lignite Energy Fuels (IF 3.024) Pub Date : 2018-12-10 Yuuki Mochizuki, Junpei Watanabe, Naoto Tsubouchi
The removal of dibenzothiophene (DBT) in a hydrocarbon liquid model fuel (MF) by Ni-loaded carbon (Ni/C) prepared from lignite has been studied with a flow-type fixed-bed reactor. The performance of Ni/C in the removal of 500 ppmw S in MF depends on the amount of Ni loaded. The highest ability is observed at 11 wt % dry Ni under the conditions of a reduction time of 0.5 h and a desulfurization temperature of 200 °C. In addition, the reduction time influences the breakthrough curves, and it is found that the optimum condition for DBT removal from MF by Ni/C is 1.0 h. When the desulfurization temperature for evaluating the DBT removal ability of Ni/C is increased, the breakthrough and saturation points also increase, and the greatest performance is observed at 200 °C. From the identification of MF treated by Ni/C, it was found that a part of DBT in the MF feed is removed by chemical adsorption via cleavage of the C–S bond in the DBT molecule to form biphenyl which can adsorb onto a carbonaceous material surface.
Mineralogical Composition Evolution and Thermogravimetric Characteristics of Sewage Sludge Ash at Different Ashing Temperatures Energy Fuels (IF 3.024) Pub Date : 2018-12-10 Lin Mu, Chen Zhao, Liang Zhao, Bowen Chen, Zhiling Xu, Zhuqiang Yang, Yan Shang, Hongchao Yin
Experiment and Modeling on Thermal Cracking of n-Dodecane at Supercritical Pressure Energy Fuels (IF 3.024) Pub Date : 2018-12-10 Dingrui Zhang, Lingyun Hou, Mingyu Gao, Xiaoxiong Zhang
A comprehensive understanding of the thermal cracking behavior of hydrocarbon fuels is important for thermal protection applications and investigations into the combustion of thermally cracked fuels. In the present study, n-dodecane is selected as a surrogate for aviation kerosene and it is subjected to a series of thermal cracking experiments at supercritical pressure. According to variations in chemical heat sink, fuel-conversion rate, and gas-production rate, the thermal cracking of n-dodecane is divided into three regions: primary, secondary, and severe. In the primary cracking region, the fuel-conversion rate is lower than 13%, and the liquid products contain only chain alkanes and alkenes. Owing to the mass fraction of main products being proportional to the fuel-conversion rate, a one-step global reaction kinetics is constructed. The secondary cracking region is characterized by rapidly increasing chemical heat sink, fuel-conversion rates, and gas-production rates with increasing fuel temperature, and the appearance of monocyclic aromatic hydrocarbons (MAHs) and cycloalkenes. A kinetic model containing three reactions is proposed for this region. This also considers the thermal decomposition of chain alkanes and alkenes, which result in the formation of MAHs and cycloalkenes. Severe cracking is observed for fuel-conversion rates above 71% where a rapid increase in the concentration of monocyclic and polycyclic aromatic hydrocarbons (PAHs) occurs. The increasing rate of chemical heat sink slows in this region which is characterized by the formation of MAHs, PAHs, and coke. A three-dimensional numerical model is built for the primary and secondary cracking regions, taking the effects of the flow, heat transfer, and thermal cracking of n-dodecane into consideration. Predicted values for the outlet temperature, fuel-conversion rate, and distribution of the main species in all tested cases agree well with the experimental results, validating the numerical model and kinetics for the primary and secondary thermal cracking of n-dodecane.
A new method for direct determination of char yield during solid fuel pyrolysis in drop-tube furnace at high temperature and its comparison with ash tracer method Energy Fuels (IF 3.024) Pub Date : 2018-12-10 Sui Boon Liaw, Hongwei Wu
A drop tube furnace with novel double-tube configuration was successfully developed to directly determine char yields during the pyrolysis of a wide range of solid fuels (mallee wood, mallee leaf, rice husk, biosolid and subbituminous, bituminous and anthracite coal) at a gas temperature of 1573 K. The char yield from pyrolysis of mallee wood and mallee leaf is <5%, ~13% for rice husk, ~16% for biosolid, ~44% for subbituminous and bituminous coal and ~75% for anthracite coal. The retentions of Na, K, Mg and Ca in biomass chars are < 50%. About 35% of Na and K and ~66–85% of P and refractory species in biosolid are retained in the char. On the contrary, the retentions of major inorganic species in coal chars are >85%. This study shows using total ash as ash tracer results in 45–220% overestimation of char yields for biomass fuels and 13–27% for coals due to partial evaporation of ash. Similarly, selecting Na and K result in overestimation of biomass char yield by at least 2.5 times while P lead to overestimation of biomass char yields by at least 80%, due to substantial release of these species during pyrolysis. Similarly, selecting Mg, Ca, Al, Fe, Ti and Si as tracer also result in inaccurate estimation of char yields due to partial release of these elements during pyrolysis. It is noted that for Si, which is often used as a tracer, the overestimation of char yields is 9-16% for coals but can be substantial (17-50%) for the case of biomass samples due to the substantial Si release during the pyrolysis of biomass (especially mallee wood with ~32% of Si released). Clearly, for the solid fuels studied, no single element can be reliably used as tracer for calculating char yield during pyrolysis at high temperature. The new experimental method developed in this study fill this critical gaps and enables directly determination of char yield during solid fuel pyrolysis in drop-tube furnace at high temperature.
EFFECT OF REACTOR CONFIGURATION ON THE HYDROTREATING OF ATMOSPHERIC RESIDUE Energy Fuels (IF 3.024) Pub Date : 2018-12-10 Fernando Alonso, Jorge Ancheyta, Guillermo Centeno, Gustavo Marroquin, REBECA SILVA RODRIGO
To study the effect of reactor configuration on hydrotreating, a series of experiments was carried out in a pilot plant equipped with two reactors in series that can operate in two modes: fixed-bed reactor (FBR) or ebullated-bed reactor (EBR). The experiments were carried out with atmospheric residue as feedstock and commercial catalysts at pressure of 100 kg/cm2 and temperature of 380°C and 400°C. The highest conversions were obtained for the EBR-EBR (35.67-52.21%), and EBR-FBR (29.08-53.09%) configurations, unlike FBR-FBR configuration that exhibited lowest conversion (15.42-27.34%). At 400°C the EBR-FBR and FBR-FBR configurations showed higher hydrodemetalization (HDM) than the others (81.00% and 76.95%, respectively). It was confirmed that the formation of sediments increases at high temperatures, where at 400°C it begins to be significant for the EBR-FBR and EBR-EBR configurations (0.010-0.767 wt.% and 0.041-0.613 wt.%, respectively), in contrast to the FBR-FBR configuration that presented lesser formation of sediments (0.003-0.009 wt.%).
Pelletization of carbonized wood using organic binders with biomass gasification residue as additive Energy Fuels (IF 3.024) Pub Date : 2018-12-10 XIN DAI, Sarut Theppitak, Kunio Yoshikawa
Integrating carbonization and pelletization becomes an attractive technology for energy usage of biomass resources. But challenges still remain for the densification of carbonized biomass. Firstly, the pellet quality by using lignin, starch and polyvinyl alcohol (PVA) as binder was compared. PVA performed the best both on the pellet strength and hydrophobicity. Furthermore, a new pelletization method by using organic binders coupled with additives was suggested to enhance the pellet strength. The strength of PVA pellet increased by employing the biomass gasification residue (BGR) as additive. Mechanism of the influence of the binder and the BGR additive to the pellet quality was discussed. Overall, applying PVA as a binder and BGR as additive could be an adequate method to produce carbonized pellet with high quality. Using BGR as additive for pelletization gives a chance to reduce the binder usage and also provides a good disposal method of the BGR.
Distribution of polycyclic aromatic hydrocarbons（PAHs）in coal gangue and emitted gas with low-temperature spontaneous combustion in situ Energy Fuels (IF 3.024) Pub Date : 2018-12-10 Xueqin Wen, Jingru Zhao, Fangui Zeng
Five coal gangue samples from the Du'erping Coal Mine in Shanxi, China, subjected to low-temperature combustion, and their emitted gas samples were collected in situ at the combustion temperatures of 23°C, 33°C, 49°C, 57°C, and 70°C. The concentrations of 16 PAHs in these samples were determined by high performance liquid chromatography (HPLC); these concentrations indicated that with decreasing combustion temperature ∑16PAHs in coal gangue tend to decrease while ∑16PAHs in emitted gas tend to increase. With the decrease of combustion temperature, the concentrations of Σ6LPAHs in coal gangue and emitted gas decreased while the concentrations of Σ10HPAHs increased; therefore, the overall toxicity and carcinogenicity increased. The total index of PAHs in the samples ranged from 20.1 to 22.425 with a mean of 21.805. The ratio of Flua/(Flua+Pyr) ranged from 0.34 to 0.97 with a mean of 0.758. Finally, the proportions of Ant/(Ant+Phe), BaA/(BaA+Chr) and InP/(InP+Bghi) were approximately 1. These ratios and the total index of the PAHs could be used to identify the source of PAHs in the atmosphere and soil.
Characterization of Temperature and Soot Volume Fraction in Laminar Premixed Flames: Laser Absorption/Extinction Measurement and Two-Dimensional Computational Fluid Dynamics Modeling Energy Fuels (IF 3.024) Pub Date : 2018-12-07 Liuhao Ma, Hongbo Ning, Junjun Wu, Kin-Pang Cheong, Wei Ren
We performed a comprehensive laser absorption/extinction study of temperature and soot volume fraction (SVF) in C2H4/air premixed sooting flames. Laser-absorption two-line thermometry at 2.5 μm provided a temperature uncertainty of 50 K compared with that of 90 K using conventional thermocouples. Laser extinction of soot at 633 nm was first validated against the previous measurements using laser-induced incandescence. All of the measurements were conducted at four representative C2H4 flame conditions (equivalence ratio Φ = 1.78, 1.95, 2.14, and 2.38). In addition, a CFD (computational fluid dynamics) framework coupling a skeletal mechanism (56 species and 428 reactions) with the Moss–Brookes model was developed for interpreting the experimental data. The current CFD simulations well predicted the temperature and SVF distribution along the centerline of flame. It is of interest to observe that the SVF depends on the Reynolds number of reactants by investigating the SVFs at different heights above the burner for the varied flow rates and equivalence ratios.
A Review of Kinetic Hydrate Inhibitors from an Environmental Perspective Energy Fuels (IF 3.024) Pub Date : 2018-12-07 Malcolm A. Kelland
Kinetic hydrate inhibitors (KHIs) have been used in the upstream petroleum industry for about 25 years to prevent plugging of flow lines with gas hydrates. The main ingredients in current commercial KHI formulations are one or more water-soluble polymers which contain both hydrophobic and hydrophilic functionalities. Although the vast majority of KHIs are low in acute toxicity and bioaccumulation, very few commercial products show good biodegradability, and for that reason, there is always some concern of long-term chronic toxicity from partially degraded products if discharged into the environment. This report reviews all efforts to develop more biodegradable KHIs, and outlines the fact that some classes of so-called “green” chemicals are not necessarily readily biodegradable or low in toxicity. The review also covers methodologies to recover or destroy KHIs and reduce their discharge to the environment.
Evaluation of Nanoscale Accessible Pore Structures for Improved Prediction of Gas Production Potential in Chinese Marine Shales Energy Fuels (IF 3.024) Pub Date : 2018-12-07 Yang Wang, Yong Qin, Rui Zhang, Lilin He, Lawrence M. Anovitz, Markus Bleuel, David F. R. Mildner, Shimin Liu, Yanming Zhu
The Lower Cambrian Niutitang and Lower Silurian Longmaxi shales in the Upper Yangtze Platform (UYP) are the most promising strata for shale gas exploration in China. Knowledge of the nanoscale pore structure may improve the prediction of the gas production potential in Chinese marine shales. A systematic investigation of the pore accessibility and its impact on methane adsorption capacity has been conducted on shale samples using various techniques including geochemical and mineralogical analyses, field-emission scanning electron microscopy (FE-SEM), small-angle neutron scattering (SANS), helium porosimetry, and methane adsorption. The results show that organic matter (OM) pores with various shapes dominate the pore systems of these shales. OM tended to mix with clay minerals and converted to organoclay complexes, developing plentiful micro- and mesopores. A unified fit model with two pore structures, fractal pores and finite pores, was used to model the SANS data to characterize the pore structure of the shales. Both mass and surface fractals are identified for each pore structure. The total porosity estimated by the Porod invariant method ranges between 2.35 and 16.40%, of which the porosity for finite pores ranges between 0.35 and 6.36%, and the porosity for the fractal pores ranges between 2.07 and 8.51%. The fraction of open pores was evaluated by comparing the porosities estimated by He porosimetry and SANS. We find that the fraction of open pores is higher than 64% for most of these shales. Correlation analyses suggest that clay and total organic carbon (TOC) have opposite effects on pore structure and methane adsorption capacity. Samples with higher clay contents have higher pore accessibility and lower total porosity, surface area, and maximum methane adsorption, whereas samples with higher TOC content show the inverse relationships. The high percentage of open pores may reduce methane adsorption capacity in these shales, whereas low pore accessibility may reduce methane production at specific pressure differences. Thus, both TOC and pore accessibility may be essential controlling factors in methane production from shale gas reservoirs.
Study on the Capture of Gaseous KCl by Cellulose Char Energy Fuels (IF 3.024) Pub Date : 2018-12-07 Wen-ting Xu, Qiang Song, Hai-bo Zhao, Jiankun Zhuo, Qiang Yao
The release of K during thermal utilization of biomass can cause fouling, slagging and other technical problems, while the released K might be recaptured by biomass char. In this work, cellulose char was used as a raw material to avoid the effects of inorganic elements in biomass char. The capture of gaseous KCl by cellulose char was examined at 900-1000 °C in a double-layer fixed-bed reactor. The temporal capture pattern was obtained based on an analysis of char samples after capture for different durations, and the stability and association of the captured K were analyzed. Cellulose char showed a remarkable ability to capture gaseous KCl. The increase in the K content captured by the char was rapid at first, decreased with time, and eventually reached 0. With the temperature increasing from 900 °C to 1000 °C, the saturated content of the captured K increased from 4.1% to 5.5% and reached saturation more rapidly. The capture abilities of char with different pyrolysis degrees were identical. The K/Cl ratio and SEM-EDS analysis of the captured char indicated that KCl capture by char occurred primarily through the reaction of the organic structure with KCl to generate char-K, and through the adsorption of KCl. Under an Ar atmosphere, the K captured in char was partially released again to the gas phase, but an amount remained stable in the char in the form of char-K. This content was approximately 1.7% and was not related to the pyrolysis temperature. The captured K existed mainly as water-soluble and insoluble K. In the thermal stability experiment, both water-soluble and insoluble K can be partly released to gas, but more insoluble K was released than water-soluble K, which meant that the ratio of water-soluble K in char obviously increased.
Removal of Elemental Mercury from Coal Pyrolysis Gas Using Fe–Ce Oxides Supported on Lignite Semi-coke Modified by the Hydrothermal Impregnation Method Energy Fuels (IF 3.024) Pub Date : 2018-12-07 Xiaoyang Zhang, Yong Dong, Lin Cui, Donghai An, Yuanyang Feng
In this paper, Fe–Ce mixed oxides supported on lignite semi-coke were prepared by the hydrothermal impregnation method. The sorbents were employed to capture elemental mercury from coal pyrolysis gas. The influences of hydrothermal impregnation temperature, mole ratio of Fe/Ce, reaction temperature, and H2S concentration on Hg0 removal efficiency were investigated in a fixed-bed reactor. The physicochemical properties of the sorbent samples were characterized by X-ray diffraction, Brunauer–Emmett–Teller, scanning electron microscopy, and X-ray photoelectron spectroscopy (XPS). The results showed that the Fe/Ce-modified semi-coke sorbents, synthesized by hydrothermal impregnated at 200 °C, had larger specific surface areas and pore volumes than the original semi-coke. The sorbent with a Fe/Ce molar ratio of 0.4:0.2 exhibited the highest Hg0 removal efficiency of 83.5% at 150 °C. On the basis of the XPS characterization of the sorbent, a mechanism of Hg0 removal over the Fe0.4Ce0.2/SC200 sorbent was proposed, suggesting that H2S could react with Fe/Ce mixed to form active sulfur, with which Hg0 could react to form HgS. In addition, the stability and regeneration of the sorbent were also investigated.
Enhanced Oil Recovery Potential of Alkyl Alcohol Polyoxyethylene Ether Sulfonate Surfactants in High-Temperature and High-Salinity Reservoirs Energy Fuels (IF 3.024) Pub Date : 2018-12-07 Rui Liu, Dai-jun Du, Wan-fen Pu, Jing Zhang, Xi-bin Fan
Surfactant flooding has been widely applied in high-temperature and high-salinity reservoirs. In this paper, the enhanced oil recovery potential of alkyl alcohol polyoxyethylene ether sulfonate (CEOS) was investigated in a combined study of surface activity, crude oil–water interfacial tension (IFT) reduction, emulsifying property, wettability improvement, and macroscopic oil displacement efficiency. The results illustrated that CEOS had high surface activity and IFT could be reduced to an ultralow level (10–3 mN/m) at high-temperature and high-salinity conditions. When salinity ranged from 15 × 104 to 22.5 × 104 mg/L and reservoir permeability was ∼10 mD, linear CEOS solution could effectively displace crude oil for its favorable IFT reduction ability. Linear CEOS or CEOS with a benzene ring was optimized for their favorable IFT reduction ability or emulsifying ability when reservoir permeability was ∼50 mD or non-homogeneous. A 0.5 pore volume surfactant flooding and subsequent water flooding could remarkably enhance oil recovery to 16.19–19.38%. All of the results indicated that CEOS has great potential for improving oil recovery in high-temperature and high-salinity oil reservoirs.
Dissolution of Asphaltene in Binary Mixtures of Organic Solvents and Model Maltenes: Unambiguous Evidence for Asphaltene Preferential Solvation and Relevance to Assessing the Efficiency of Additives for Asphaltene Stabilization Energy Fuels (IF 3.024) Pub Date : 2018-12-07 Luzia P. Novaki, Nicolas Keppeler, Michelle M. N. Kwon, Letícia T. Paulucci, Márcia C. K. de Oliveira, Francis A. Meireles, Wilhelm J. Baader, Omar A. El Seoud
Asphaltenes (Asps) are operationally defined as the toluene-soluble but n-pentane- or n-heptane-insoluble fractions, e.g., of crude oils. Therefore, there is intense interest in determining the concentration of n-heptane required to precipitate Asps from their solutions in particular media (solvents, solvent mixtures, and maltenes). Here, we report on the dependence of Asp dissolution in binary mixtures of n-heptane (solvent 1, S1)/organic solvent (solvent 2, S2) over the entire mole fraction range of S2, χS2, and in few selected maltene models (n-heptane + S2 + benzothiazole + n-octyl-1-napthoate). The S2 employed were benzonitrile, cyclohexanone, ethyl benzoate, 1-methylnaphthalene, tetrahydropyran, and toluene. For all S2 and model maltenes, the dependence of wt % dissolved Asp (determined by mass and UV/vis absorbance) on χS2 was nonlinear. We attribute this nonlinear, i.e., nonideal dissolution behavior to “preferential solvation” of the Asp by a component(s) of the medium (binary solvent mixtures and maltenes). Although the occurrence of “solvent sorting” during Asp dissolution was alluded to, this is the first direct and unambiguous evidence for its occurrence. We used solvatochromism to corroborate our rationale about the origin of the Asp nonideal dissolution behavior. The term solvatochromism refers to the effect of the solvent on the color of solvatochromic probes, substances whose spectra are sensitive to the properties of the liquid medium, e.g., its empirical polarity, ET(probe). Recently, we used (E)-2,6-di-tert-butyl-4-[2-(1-hexylquinolin-1-ium-4-yl)vinyl]phenolate, HxQMBu2) to study Asp dissolution in pure solvents and model maltenes. We showed that ET(HxQMBu2) correlates linearly with Hildebrand solubility parameters of pure solvents as well as with lg (wt % dissolved Asps). In the present work, we studied the solvatochromic response of HxQMBu2 in the above-mentioned n-heptane/S2 binary mixtures. Except for toluene/n-heptane mixtures, plots of ET(HxQMBu2) versus χS2 were nonlinear due to probe preferential solvation. We successfully fitted a solvation model to the solvatochromic and Asp dissolution data and extracted the enrichment of the solvation layers in the more polar component(s) of the binary mixture and model maltenes. Our results bear on the assessment of additives employed to stabilize Asps: in the absence of adverse effects of the additive on other properties (e.g., viscosity and water/oil emulsion stability), efficient additives should accumulate in the solvation layer of Asp particles where they displace the nonsolvents, e.g., the saturates.
Design of CO2-in-Water Foam Stabilized with Switchable Amine Surfactants at High Temperature in High-Salinity Brine and Effect of Oil Energy Fuels (IF 3.024) Pub Date : 2018-12-07 Chang Da, Guoqing Jian, Shehab Alzobaidi, Jonathan Yang, Sibani L. Biswal, George J. Hirasaki, Keith P. Johnston
The design of surfactants for CO2-in-water (C/W) foams in carbonate reservoirs above 100 °C has been limited by thermal instability of surfactants, surfactant adsorption to mineral surfaces, and challenges in generating and stabilizing the foams. Here, we have identified a diamine surfactant, C12–14N(CH3)C3N(CH3)2 (Duomeen CTM), with good thermal stability (>1 month at 135 °C), that stabilizes viscous C/W foam with an apparent viscosity of up to ∼35 cP at 120 °C in 22% total dissolved solid (TDS) brine. Strong foams with excessively high viscosity were reported to be generated with longer-tailed C16–18N(CH3)C3N(CH3)2 (Duomeen TTM) that formed a viscoelastic aqueous phase. Here, the tail length was shorter for C12–14N(CH3)C3N(CH3)2 and thus a viscoelastic aqueous phase was not formed, resulting in a weaker CO2 foam with a more appropriate viscosity for the proposed applications. Moreover, at the lowest superficial velocity studied (4 ft/day), the apparent viscosity for C12–14N(CH3)C3N(CH3)2 was ∼20 fold lower than that of C16–18N(CH3)C3N(CH3)2, consistent with the lower viscosity for the aqueous phase. Not only the foam viscosity with C12–14N(CH3)C3N(CH3)2 was high enough for CO2 mobility control in enhanced oil recovery (EOR) but also it was low enough to be more favorable with regard to the injection pressure than the excessive high flow resistance associated with C16–18N(CH3)C3N(CH3)2. In addition, viscous C/W foam was maintained at low fractions of dodecane (model oil) and broke in the presence of large fractions of dodecane, both of which are beneficial to EOR. The oil/water (O/W) emulsions formed with C12–14N(CH3)C3N(CH3)2 were unstable and broke in 30 min, and the O/W partition coefficient depended greatly on pH at 120 °C in 22% TDS brine. All of these factors suggest that the surfactant C12–14N(CH3)C3N(CH3)2 is a good candidate for further evaluation and scale up for CO2 EOR, CO2 sequestration, and hydraulic fracturing at high salinities and temperatures.
Effects of Salt Ions on the Methane Hydrate Formation and Dissociation in the Clay Pore Water and Bulk Water Energy Fuels (IF 3.024) Pub Date : 2018-12-07 Guozhong Wu, Haoqing Ji, Linqing Tian, Daoyi Chen
Gas hydrates in marine sediments are promising energy resources, while an effective recovery of methane from clay pores relies on a comprehensive appreciation of the hydrate evolution inside and outside the pore especially at a saline environment. Molecular dynamics simulations were conducted to investigate the methane hydrate formation and dissociation in the sodium montmorillonite (Na-MMT) interlayer with fresh water and saline water, respectively, by characterizing the distribution and transportation of methane and ions (K+, Na+, and Ca2+), the overall and local four-body structural order parameter, and the radial distribution functions. Results indicated that it was much easier to form methane hydrates in the bulk water than in the pore water, while the hydrates in the pore region were more readily dissociated than in the bulk region. The effects of salt ions on the hydrate formation were opposite in these two regions, which highlighted the role of the salting-out effect and the ion exchange between bulk water and pore water on the hydrate formation dynamics. It also demonstrated the priority for the hydrate dissociation from the contact area between MMT edge and bulk water because this region is more favorable for the distribution of salt ions and is more susceptible to be perturbed by the diffusion of salt ions from the pore water. Overall results provided theoretical supports for better understanding the microscopic mechanisms for the methane hydrate evolution at the heterogeneous environment with salt ions.
Speciation and Thermal Stability of Mercury in Solid Products from Ultralow Emission Air Pollution Control Devices Energy Fuels (IF 3.024) Pub Date : 2018-12-06 Chenghang Zheng, Linjie Xu, Shaojun Liu, Li Wang, Chengsi Liang, Haitao Zhao, Yongxin Zhang, Xuesen Du, Xiang Gao
The thermal stability of mercury (Hg) is a key factor that influences its solidification. However, the thermal stability of Hg in ultralow emission coal-fired power plants remains unclear. This study aimed to employ the temperature-programmed desorption technique to identify the forms and mass distribution of Hg species in solid products across air pollution control devices (APCDs) in typical ultralow emission coal-fired power plants. The migration mechanism of Hg across APCDs was determined by comparing the Hg species present in different solid samples. Furthermore, the impacts of different ultralow emission pollution control devices on Hg migration were obtained by comparing Hg compounds in solid products from different units. Results showed that Hg in the fly ash was mainly in the form of HgCl2 (41–47%) and HgS (43–47%). HgCl2 tended to be abundant in fine particles, and HgCl2 accounted for 90.68% of Hg in wet electrostatic precipitator (WESP) slag. HgCl2 (28–29%) and HgS (21–85%) were the dominant Hg species in gypsum. Hg in the waste sludge was mainly HgS. The corresponding temperatures of the release rate of 90% Hg in fly ash, gypsum, waste sludge, and WESP slag were in the range of 333–362, 350–637, 290–654, and 188–455 °C, respectively. The total Hg thermal stability of solid products increased in the order of gypsum > waste sludge > fly ash > WESP slag.
Evaluation of Wax Inhibitor Performance through Various Techniques Energy Fuels (IF 3.024) Pub Date : 2018-12-06 Jeramie J. Adams, Frederic TORT, John F. Schabron, Jenny L. Loveridge, Joe Rovani, Khalid Baig
Various techniques were used to compare the effectiveness of a commercially available wax inhibitor (WIA) to a newly developed wax inhibitor (WIEP) using a highly waxy Wyoming crude oil—which causes plugging within wellbores and pipelines. The two additives were compared using centrifuge experiments, cold finger tests, and the precipitation and redissolution waxphaltene determinator (WD) method. Centrifuge tube experiments, and cold finger tests, showed that the newly developed WIEP additive was significantly more effective at reducing the amount of ambient temperature wax crystallites in the crude oil, as well as reducing the amount of wax deposited on a cold finger. WD analysis was performed on model compounds to differentiate between shorter and longer n-paraffins. Whole crude oils, ambient temperature waxes centrifuged from the oils, and waxes from cold finger deposits were also analyzed by the WD method. Taken together with high temperature gas chromatography, the WD profile of whole crude oils readily distinguishes shorter n-paraffins from the more problematic longer n-paraffins that are prone to crystallization at ambient temperature. For treated Elliott crude oil, the WD Analysis profile showed a consistent decrease in wax with WIA concentration to give a linear correlation; however, a less consistent change was observed with the WIEP additive. By applying the WD analysis to the additives themselves, it was elucidated that the WIEP additive contained components that were highly polar and/or more associated. This observation suggests that components in the WIEP additive may self-precipitate to a greater degree than becoming incorporated with the waxes during the WD separation. This effect caused the WIEP to appear as though it is not as effective as the WIA additive in the WD analysis.
Hydrogen and carbon isotope composition of hydrocarbon gases generated during pyrolysis of peats from different environments Energy Fuels (IF 3.024) Pub Date : 2018-12-06 Yi DUAN, Mingchen Duan, Yingzhong Wu, Jingli Yao, Zhongping Li, Lantian Xing, Yan Liu
For the purpose of understanding whether the formation environment of peat precursor has a meaningful effect on the isotope ratios of thermogenic coalbed gas, the pyrolysis experiments were carried out on herbaceous and reed marsh peats derived from high-latitude areas with cold dry climate and an herbaceous peat of low-latitude area with tropical moist climate. Our results show that the hydrocarbon gases generated from herbaceous swamp peat of the high-latitude area had lighter hydrogen (–56‰ to –46‰) and heavier carbon (3.3‰ to 8.2‰) isotopic compositions than those generated from the low-latitude area peat. As the peat samples were pyrolytically matured to vitrinite reflectance levels of 2.5, 3.5 and 5.5%, respectively, the hydrogen and carbon isotope ratios of the generated hydrocarbon gases increased, and the average hydrogen isotopic differences between them decreased from –32‰ to –10‰ while the carbon isotopic differences increased from 0.9‰ to 3.6‰, respectively. We suggest that the cause of these differences may come mainly from the environmental influence on hydrogen and carbon isotopic compositions of the peats. Our results also showed that the influence of the formation environment of peat precursor on the isotopic compositions of the pyrolysis hydrocarbon gases is less than that of types of the peat. A good positive correlation of δD or δ13C value with maturity as well as δD value with δ13C value of the generated hydrocarbon gases was existent between the two kinds of samples, respectively, and their mathematical expressions were also established. These results showed that the environmental influence on isotopic compositions of peat should be considered when evaluating the genesis of thermogenic coalbed gas using hydrogen and carbon isotopes.
Effects of H2S on the reactivity of ilmenite ore as chemical looping combustion oxygen carrier with methane as fuel Energy Fuels (IF 3.024) Pub Date : 2018-12-06 Yewen Tan, Zhenkun Sun, Arturo Cabello, Dennis Y. Lu, Robin Hughes
A series of experiments were carried out in a pressurized thermogravimetric analyzer (PTGA) to study the effects of H2S on the reactivity of ilmenite oxygen carrier under pressurized conditions. The total pressure was maintained at 0.4 MPa(absolute). Methane was used as fuel and its partial pressure varied from 0.08-0.119 MPa. The concentration of H2S varied from 2020 ppm to 3030 ppm. The test temperature ranged from 1073-1173 K. The results showed that the reactivity of the ilmenite oxygen carrier improved with the presence of H2S, for both the reduction and the oxidation steps. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and X-ray photoelectron spectroscopy (XPS) analyses were conducted to assess sulfur deposition on the reduced ilmenite samples. Thermodynamic analyses were performed to help interpret the test results. A kinetic model was developed based on the experimental results. The model showed an activation energy for ilmenite reduction with H2S at ~79 kJ mol-1 when H2S was present and 104 kJ mol-1 for pure methane.
Effect of short-time hydrothermal carbonization on the properties of hydrochars prepared from olive-fruit endocarps Energy Fuels (IF 3.024) Pub Date : 2018-12-06 Manuel Cuevas, Maria Lourdes Martinez Cartas, Sebastian Sánchez
Endocarps of the olive fruit were subjected to short-time hydrothermal carbonization (SHTC) to study the effect of temperature and holding time on the properties of hydrochars. In general, the increase of these variables improved the calorific value and the combustion properties of the hydrochars, and decreased their capacity to adsorb moisture and the ash content. Best hydrochar was produced at 225 °C for 10 min, showing maximum values of higher calorific value (23.4 MJ/kg), energy efficiency (74.7%) and comprehensive combustibility index (6.14 × 10–7 min–2 ºC–3), higher values than those were managed working at 250 ºC. The increase in energy efficiency at 225 °C at longer reaction residence times was related to repolimerization phenomena studied by mean of the analysis of the structural components of the biomass (fiber analysis), SEM inspection and Fourier-transform infrared spectroscopy (FTIR). Finally, the pyrolysis of the olive endocarp could be mathematically modeled, from thermogravimetric analysis, concluding that this process requires higher temperatures to remove volatile materials of the biomass, in comparison with the SHTC.
Comparative Investigations on Wettability of Typical Marine, Continental, and Transitional Shales in the Middle Yangtze Platform (China) Energy Fuels (IF 3.024) Pub Date : 2018-12-06 Rui Yang, Sheng He, Qinhong Hu, Gangyi Zhai, Jizheng Yi, Li Zhang
Wettability is a physico-chemical rock property that plays a crucial role in the efficient development of shale gas and oil. However, a precise characterization of wettability for shale reservoirs is still a challenging task because of their complex pore structure (with a large proportion of pores in nm scale) and shale composition (variable at μm scale). In this work, we conducted the fluid drop wettability test, air–liquid contact angle measurement, and spontaneous imbibition (SI) with two fluids [deionized (DI) water and n-decane (an oil phase)] to evaluate the wettability of typical organic-rich shales (marine Longmaxi, continental Dongyuemiao, and transitional Dalong and Longtan shales), as influenced by total organic carbon (TOC), thermal maturity, mineral composition, effective porosity, and pore size distribution. Marine Longmaxi shales have strong or moderately strong water-wet properties with measured DI water contact angles of 3.4°–16.5°. In contrast, continental Dongyuemiao and transitional Dalong–Longtan shales show a much stronger water-repellant property with contact angles in the ranges of 21.2°–46.4° and 57.8°–61.7°, respectively. N-decane spreads quickly on the flat sample surfaces to generate zero contact angles, indicating that all these shales are strongly oil-wet. This is consistent with the much larger imbibition slopes of n-decane in the plot of log dimensionless weight (WD) versus log dimensionless time (tD) than DI water. Shale samples with the higher TOC content, higher quartz content, and lower clay content have a stronger water-repellant property in marine Longmaxi and continental Dongyuemiao shales. In contrast, relationships between DI water contact angles and quartz content and clay content are not obvious in transitional shales. With thermal maturities increasing from mature to high-mature and overmature, wetting affinity to DI water tends to alter, which needs more comprehensive investigations in the future. Effective porosity has a positive effect on DI water contact angles for argillaceous limestones in continental Dongyuemaio, siliceous shales in marine Longmaxi, and transitional shales, whereas it has a negative effect in the silty shales from continental Dongyuemiao and argillaceous siliceous shales from marine Longmaxi.
High Heating Rate Devolatilization Kinetics of Pulverized Biomass Fuels Energy Fuels (IF 3.024) Pub Date : 2018-12-05 Joakim M. Johansen, Peter A. Jensen, Peter Glarborg, Nikolai De Martini, Paul Ek, Reginald E. Mitchell
Devolatilization kinetics for the biomass fuels miscanthus, leached miscanthus, and KCl-doped pinewood were determined at high heating rates (∼105 K s–1), high peak temperatures (1405–1667 K), and short residence times (<70 ms). The particle temperature and residence time distribution were obtained from computational fluid dynamic simulations. The measured devolatilization rates, formulated in terms of single first-order reactions, were significantly faster than data reported in the literature. This difference was attributed partly to the fast heating rate/high-temperature conditions of the present study and partly to a more accurate estimate of the particle temperature. The current results indicate that neither the biomass type nor the alkali content of the biomass has a significant impact on the devolatilization rate under the investigated conditions. The development in the particle morphology was studied by electron microscopy as each fuel underwent partial to full conversion. The char yields ranged from 0.02 (leached miscanthus) to 0.11 (KCl-doped pinewood), indicating that even during fast heating, the biomass alkali content promotes char formation.
Hydrocarbon generation potential of Oligocene oil shale deposit at onshore Penyu Basin, Chenor, Pahang, Malaysia Energy Fuels (IF 3.024) Pub Date : 2018-12-05 Yousif Makeen, Wan hasia Abdullah, HABEEB AYINLA, Mohammed Hakimi, Xuanlong Shan, Khairul Azlan Mustapha, Mustaffa Kamal Shuib, Muhammad Nadzmi Abdul Ghofur, Ye Liang, Nor Syazwani Zainal Abidin
This is the first study that focuses on the evaluation of a newly-discovered oil shale deposit in the eastern Chenor area in the state of Pahang, Malaysia. Previously, this deposit was reported as carbonaceous/coaly mudstone. However, in this study, organic-rich immature carbonaceous mudstone containing above 15 wt % TOC is evaluated as oil shale, and that below 3.5 wt % TOC is termed mudstone. Oil shale and mudstone, which are significant sedimentary facies for oil and gas exploration, were investigated using organic geochemical and petrological methods, as well as Computed Tomography (Micro- CT), pyrolysis and bulk kinetic techniques, to evaluate their hydrocarbon generation potential. The vitrinite reflectance values are less than 0.5 %Ro in all of the analyzed samples, indicating low maturity stage. This is corroborated by Tmax values ranging from 383 to 429 °C. However, based on the kinetic simulation model, the average of predicted geological temperature for onset of hydrocarbon generation is 109 °C, while the peak of hydrocarbon generation is 153 °C. The extractable organic matter and hydrocarbon contents results show that the oil shale samples possess excellent petroleum potential compared to very good values for the studied mudstone. This is consistent with the plots of TOC content versus extractable organic matter, and hydrocarbon yields versus TOC content, commonly used in estimating the hydrocarbon generative potential of source rocks. The TOC of these oil shales are consistent with those of the Tertiary oil shale deposits in China. The analysed oil shale samples are characterized by a high hydrogen index (HI) of up to 700 mg HC/g TOC (average 517.4 mg HC/g TOC), suggesting oil-prone Type I and Type II kerogens. However, the open pyrolysis-gas chromatography (Py-GC) result of these samples displays a predominance of n-alkene/n-alkane doublets extending to the long range homologous series (C7-C33) with considerably high aromatic compounds, which indicates Type II/III keroges (mixed oil and gas) generative potential. Similarly, bulk kinetic analysis of the analysed samples suggest typical petroleum source rocks facies derived from heterogeneous (Type II/III kerogens) organic matter assemblages. Thus, based on the pyrolysis and bulk kinetic result, the studied oil shale can be classified as ‘‘cannel coal’’ derived from terrestrial plants materials. This is supported by organic petrological and Micro-CT studies which revealed that the samples composed mainly of liptinite (sporinite, cutinite, amorphous organic matter and resinite), vitrinite, with varied trace amounts of inertinite.
ACQUIRING INFORMATION ON TOTAL CONTENT AND SPECIATION OF SILICON IN PETROLEUM PRODUCTS/FUELS USING HIGH-RESOLUTION CONTINUUM SOURCE FLAME ATOMIC ABSORPTION SPECTROMETRY AND WAVELENGTH DISPERSIVE X-RAY FLUORESCENCE Energy Fuels (IF 3.024) Pub Date : 2018-12-05 Zofia Kowalewska, Karolina Brzezińska, Katarzyna Cikorska, Janusz Pilarczyk, Łukasz Gościniak
Various chemical forms of silicon (Si), possible present in petroleum products/fuels, were investigated in this work: low molecular mass species of different composition, structure and volatility as well as oil Conostan standard, polysiloxanes and silicon dioxide. Analysis in xylene solutions was accomplished using wavelength dispersive X-ray fluorescence (WD XRF) or high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS). Samples were also analysed, using HR-CS FAAS, in aqueous solutions after: mineralization in closed microwave heated system, mineralization in open system or the mineralization combined to fusion with lithium metaborate. It was found that none of the applied procedures was suitable for accurate determination of Si in all the tested forms. The total content of Si can be only known, if various methodological variants are applied. Using WD XRF similar signals are obtained for all the investigated organic Si forms. The procedure is also helpful to detect sedimentation (presence) of inorganic Si compounds (successive measurements in the same cup). In direct measurements of organic solutions using HR-CS FAAS analytical response is similar for all the investigated organic forms, apart from the significantly increased signal for the most volatile forms. On the other hand, underestimated results were stated due to losses of volatile and medium volatile Si compounds and/or difficulty in analyte transferring to an aqueous solution in the procedures comprising mineralization. The procedure combining mineralization and fusion gives quantitative results for SiO2, Conostan standard and some polysiloxanes. Similar behavior of Si compounds belonging to a given group (organic very volatile, medium volatile, non-volatile or inorganic) and leading to a systematic error in a given procedure was used to acquire knowledge on the presence of this kind of Si species in a sample. The proposed proceedings scheme, employs easy available analytical techniques and can be widely applied. It was found, that internal standard calibration, available in HR-CS FAAS, does not correct chemical interference due to the LiBO2 matrix. However, using vanadium (V) as internal standard, it is possible to correct sensitivity drift in time.
Numerical simulation of moderate temperature desulfurization in circulating fluidized bed reactor considering sorbent abrasion Energy Fuels (IF 3.024) Pub Date : 2018-12-05 Wei Zhang, Haiming Wang, Dongwu Chang, Changfu You
A computational platform was developed to model the desulfurization process in a circulating fluidized bed (CFB) reactor at moderate temperature range (873K-1073K). The model coupled the gas-solid multiphase flow, sorbent particle abrasion and desulfurization reaction based on MFIX coding. Particle distribution characterization (PDC) was applied to modify the drag force for gas-solid interaction calculation. The modified model provides higher accuracy than the widely used homogeneous drag model as validated by the experimental data. Based on simulation results, the abrasion of sorbent particles in CFB leads to about 10% decrease in desulfurization efficiency. The CFB inventory weight is found to have significant influence on the removal efficiency by affecting the multiphase flow field, sorbent particle abrasion, and the desulfurization reactions. There exists an optimum bed inventory weight to achieve high efficiency while at low operational cost. In this study, a bed inventory of Pinv=0.5 was found to be the optimum condition with the desulfurization efficiency of 59% and the pressure drop of ~400 Pa. The established model offers a more accurate way to simulate the desulfurization process and sheds light on the design and operation of a CFB reactor for desulfurization.
Insights into the Pore-Scale Mechanism for the Low-Salinity Effect: Implications for Enhanced Oil Recovery Energy Fuels (IF 3.024) Pub Date : 2018-12-04 Z. L. Liu, T. Rios-Carvajal, M. P. Andersson, M. Ceccato, S. L. S. Stipp, T. Hassenkam
Surface and Interface Characterization of Asphaltenic Fractions Obtained with Different Alkanes: A Study by Atomic Force Microscopy and Pendant Drop Tensiometry Energy Fuels (IF 3.024) Pub Date : 2018-12-04 Iago Oliveira, Larissa Gomes, Elton Franceschi, Gustavo Borges, Juliana F. de Conto, Flávio Cortinas Albuquerque, Claudio Dariva
Hydrotreating of Model Mixtures and Catalytic Fast Pyrolysis Oils over Pd/C Energy Fuels (IF 3.024) Pub Date : 2018-12-04 Richard J. French, Kellene A. Orton, Kristiina Iisa
Noble metal catalysts may be attractive for hydrotreating of catalytic fast pyrolysis (CFP) oils. Model mixtures of raw noncatalytic fast pyrolysis and CFP oils representative of upgrading over HZSM-5 were hydrotreated in a batch reactor at 250–360 °C with palladium/carbon catalyst and 100 bar (cold) of hydrogen. The CFP oils gave high carbon yields of >95%, consumed less hydrogen per gram of oil produced, and had lower final oxygen concentrations than the raw oils did. GC/MS results were consistent with hydrogenation of alkenes and some oxygen-functionalized aromatic rings (e.g., phenolics) followed by hydrodeoxygenation at 360 °C. Complete deoxygenation was not obtained, and higher temperatures are recommended. The model oils’ chemical transformations, carbon yields, and deoxygenation were similar to those of oils produced in a bench-scale reactor with HZSM-5 catalyst.
Structural features and pyrolysis behaviors of extracts from microwave-assisted extraction of a low rank coal with different solvents Energy Fuels (IF 3.024) Pub Date : 2018-12-05 Yankun Xiong, Lijun Jin, Yang Li, Zhou Yang, Haoquan Hu
Microwave-assisted extraction (MAE) of a low rank Naomaohu (NMH) coal was conducted with two solvents, cyclohexanone (CYC) and tetrahydrofuran (THF), to obtain extracts (ECYC and ETHF) and residues (RCYC and RTHF). The parent coal, extract, and residue were characterized by ultimate analysis, TG, FT-IR, GPC, 1H NMR and solid state 13C NMR. The results showed that MAE process is more efficient than Soxhlet extraction. The solvent CYC exhibits higher total extract yield of 8.3 wt.% than THF being 4.7 wt.% during MAE, and more efficiency in extracting organic components of NMH coal, especially condensed arenes and macromolecular compounds. The average molecular weight of ECYC is higher than that of average aromatic cluster of NMH coal. Online pyrolysis-vacuum ultraviolet photoionization mass spectrometry was taken to determine the initial pyrolysis products of parent coal, RCYC and ECYC. The distribution of initial pyrolysis products suggested that NMH coal and ECYC possess similar basic arene structures, and ECYC is rich in macromolecular cluster with lots of side chains and bridge bonds. The chemical structure of ECYC could reflect the macromolecular network structure of NMH coal to some extent. This could be an effective method to understand the organic structure of coal.
Effect of Coordinated Air-Pollution Control Devices (APCD) on Trace Elements Emissions in Ultra-low Emission Coal-Fired Power Plant Energy Fuels (IF 3.024) Pub Date : 2018-12-05 Jiawei Wang, Yongsheng Zhang, Zhao Liu, Yongzheng Gu, Pauline Norris, Hong Xu, Wei-Ping Pan
In this study, the partitioning of trace elements (TEs) in an ultra-low emission coal-fired electric power plant (EPP) was investigated. TEs distribution, partitioning concentration, balance rate, and removal efficiency were evaluated. Results include determination of the TEs in flue gas, coal, fly ash, bottom ash, gypsum, limestone, makeup water, wet flue gas desulfurization (WFGD) wastewater and wet electrostatic precipitator (WESP) wastewater. The results indicate that most of the TEs are distributed in the fly ash, with a smaller portion in the bottom ash. The concentration of TEs in the flue gas gradually decreases as the gas moves through the air pollution control devices (APCDs). Only a small amount of TEs are emitted from the stack (Be: 0.039 µg/m3, Cd: 0.019 µg/m3, Cr: 2.229 µg/m3, Ni: 0.350µg/m3, Pb: 0.194µg/m3, Sb: 0.017µg/m3, Se: 0.307µg/m3 and U: 0.029µg/m3). The content of most TEs in water had little effect on the TEs balance, and the proportion of Se in liquid is quite high on the TEs balance, reaching 26.12%, which has a great influence on the balance of TEs. The low temperature economizers-electrostatic precipitator (LTE-ESP) removal efficiencies for Pb, Sb and U are between 84~96%, but the removal efficiency of the LTE-ESP unit for Be is only 42.17%. The WFGD removal efficiencies for Ni and Se were 69.39 and 82.12%, respectively. The WFGD removal efficiencies for the other TEs were less than 33.33%. Both WFGD and WESP contribute towards removing TEs. The APCDs were able to remove 99.97, 99.82, 99.86, 99.35, 99.98, 99.96, 99.48 and 99.97% of the Be, Cd, Cr, Ni, Pb, Sb, Se and U, respectively, from the flue gas stream. The application of LTE-ESP + WFGD + WESP can effectively control the emission of TEs in ultra-low emission plant.
Potential and constraints of biogenic methane generation from coals and mudstones from Huaibei coalfield, eastern China Energy Fuels (IF 3.024) Pub Date : 2018-12-04 Yuan Bao, Yiwen Ju, Haiping Huang, Juanli Yun, Chen Guo
Coalbed methane (CBM) resources formed biogenically and thermogenically have been discovered in the Permian coalbeds of the Huaibei coalfield. Four coals, three mudstones, and five coalbed-produced water samples collected from the Linhuan, Luling and Haizi coal mines of the Huaibei coalfield were characterized geochemically and biologically to gain an understanding of the biogenic methane generation potential and the microbial communities involved in situ and in coalbed-produced water enriched samples. The 16S rRNA gene high throughput sequencing results showed that the archaeal communities from in situ and enriched cultures were dominated by Methanolobus and Methanobacterium species. The organic material of coals and mudstones could be biodegraded under an anaerobic incubation. The maximum biogenic methane generation potentials of coal and mudstones were 98.5 and 72.5 µmol/g within 123 days, respectively. Volatile matter and total organic carbon (TOC) content were the most important internal factors affecting biogenic methane generation from coals and mudstones. The Na-SO4 water type resulted in a low methane generation potential.
Systematic Investigation of Asphaltene Deposition in Wellbore and Near-Wellbore Region of a Deepwater Oil Reservoir under Gas Injection. Part 2: Computational Fluid Dynamics Modeling of Asphaltene Deposition. Energy Fuels (IF 3.024) Pub Date : 2018-12-04 Narmadha Rajan Babu, Pei-Hsuan Lin, Mohammed I. L. Abutaqiya, Caleb J. Sisco, Jianxin Wang, Francisco M. Vargas
Asphaltene deposition during oil production is a major flow assurance problem. Asphaltene deposit layer reduces the pipe cross-section leading to a significant reduction in flow rate and eventually plugging the pipeline. This flow assurance problem caused during oil production has motivated the development of several experimental and modeling techniques to investigate the asphaltene behavior. This study proposes an integrated approach to simultaneously model asphaltene precipitation, aggregation, and deposition on a single platform. It focuses on the development of a deposition simulator that performs thermodynamic modeling using the Perturbed Chain version of the Statistical Associating Fluid Theory Equation of State (PC-SAFT EOS) and depicts the deposition profile by means of a Computational Fluid Dynamics (CFD) model based on finite element method. In this work, asphaltene deposition risk was assessed in the near-wellbore region and the production tubing as a result of gas-breakthrough. To achieve this goal, a sample of crude C2 was analyzed to determine its properties, and also the tendency of the asphaltenes contained in this sample to precipitate and deposit under various conditions. Laboratory scale experiments were performed to analyze the rates of asphaltene precipitation, aggregation, and deposition. With the results obtained from the various experiments, advanced modeling methods based on PC-SAFT EOS and CFD models were calibrated and used to predict asphaltene precipitation and deposition under field conditions. Simulation methods for oil flow and asphaltene precipitation in the near-wellbore region of the reservoir and inside the production tubing were coupled to provide the most rigorous modeling approach ever developed to understand and predict this complex flow assurance problem. The results show low to moderate asphaltene deposition rate produced by crude C2 as the gas breaks through. Nevertheless, further investigation is recommended to analyze the effect of other fluids that may be co-produced to enhance our ability to understand and predict asphaltene deposition under different conditions.
Electric Field Assisted Technology for Improving the Screening and Application of a Thiophene-Biodegrading Strain Energy Fuels (IF 3.024) Pub Date : 2018-12-04 Chaozheng Zhang, Lin Huang, Qiaoqiao Tang, Ying Xu, Xiaotong Lan, Jie Li, Wei Liu, Hua Zhao
For the screening of functional strain and biodegradation, two devices of electric field assisted screening (EFAS) and electric field assisted biodegradation (EFAB) were developed in the current work. Candida tropicalis CZ12 capable of thiophene degradation was enriched and isolated from oily soil by the EFAS device at a voltage range of 10–14 v. In EFAB, the thiophene degradation velocity of this strain was accelerated by an assisted electric field, and it could reach 74% at 2 h in aqueous thiophene solution. Furthermore, the removal efficiency of the continuous EFAB device for treating thiophene-containing model fuel was 79.76% under the following conditions: aqueous–hydrocarbon ratio of 5:1, electric field assisted voltage of 15 V, and residence time of 120 min. It was clear that the above advantages of EFAS and EFAB were conducive to facilitating applications in biorefractory organics.
Tribological Testing of Metallurgical Coke: Coefficient of Friction and Relation to Coal Properties Energy Fuels (IF 3.024) Pub Date : 2018-12-03 Hannah Lomas, Richard Roest, Tizshauna Thorley, Adam Wells, Hui Wu, Zhengyi Jiang, Richard Sakurovs, Sharna Wotherspoon, Richard A. Pearson, Merrick R. Mahoney
Integrated Process of Coal Pyrolysis with Steam Reforming of Ethane for Improving the Tar Yield Energy Fuels (IF 3.024) Pub Date : 2018-12-03 Yong Wu, Yang Li, Lijun Jin, Haoquan Hu
A new process to integrate coal pyrolysis with steam reforming of ethane (CP-SRE) using Ni/Al2O3 as a catalyst was proposed to improve the tar yield of coal. Coal tar of the CP-SRE process was compared to that of pyrolysis in atmospheres of nitrogen (CP-N2), hydrogen (CP-H2), and steam reforming of methane (SRM). The results showed a high tar yield in CP-SRE; it is 15.34% on a dry and ash-free basis at a temperature of 600 °C, which is 1.42, 1.09, and 1.04 times the tar yield of CP-N2, CP-H2, or CP-SRM, respectively. To understand fraction distribution and structural information on tar in CP-SRE, coal tar was characterized by simulated distillation, 1H and 13C nuclear magnetic resonance, and gel permeation chromatography. It indicated that the tar from CP-SRE presents a lower molecular weight distribution, higher light oil content, lower asphaltene content, and slightly higher amount of uncondensed aromatic protons and quaternary aromatic carbons than that from CP-N2. The coal tar formation mechanism in CP-SRE was investigated using the isotope trace method with deuterium oxide (D2O) and deuterated ethane (C2D6) as tracer agents. The results indicated that D2O and C2D6 contribute to coal tar formation in the form of activated free radicals, including •D, •CD3, •C2D5, etc.
Supercritical-Pressure Heat Transfer, Pyrolytic Reactions, and Surface Coking of n-Decane in Helical Tubes Energy Fuels (IF 3.024) Pub Date : 2018-12-03 Xing Sun, Keke Xu, Hua Meng
Supercritical-pressure heat transfer of a hydrocarbon fuel has practical importance in fuel precooling technology in hypersonic air-breathing propulsion systems. Heat transfer of n-decane in helical tubes is numerically studied at a supercritical pressure of 5 MPa, with consideration of endothermic fuel pyrolysis and surface carbon deposition. The effects of helical curvature on temperature variations, pyrolytic chemical reactions, and surface coking are analyzed. Results indicate that, owing to the centrifugal force and secondary flows, the averaged wall temperature in a helical tube is significantly reduced in the inlet region (x/D < 50). The fluid temperature is higher on the inner side of the helical tube, and as a result, the pyrolytic chemical reactions and heat absorption rates become correspondingly higher. With around 50% n-decane thermally decomposed at the tube exit, the bulk fluid temperature can be decreased up to 120 K. The coking precursors produced from fuel pyrolysis cause surface carbon deposition, and the coking amount on the inner side of the tube wall, with stronger fuel pyrolysis, is around twice that on the outer side. An empirical heat transfer correlation is found to work well for predicting supercritical-pressure heat transfer of n-decane in helical tubes, with or without fuel pyrolysis.
Controls on Hydrogen Sulfide Formation and Techniques for its Treatment in the Binchang Xiaozhuang Coal Mine , China Energy Fuels (IF 3.024) Pub Date : 2018-12-04 Chao Zhang, Renhui Cheng, Shugang Li, Lei Qin, Chao Liu, Jie Chang, Hua Liu
To determine the main factors controlling hydrogen sulfide enrichment in coal mines, the #4 coal seam in the Binchang Xiaozhuang coal mine, China, was investigated. A new hydrogen sulfide control method was also tested on this seam. Using coal petrography, X-ray diffraction, and other techniques, the reactions that generated the hydrogen sulfide in the Xiaozhuang coal were investigated. The main controlling factors that affect the physical and chemical properties of coal and its H2S are analyzed from the perspectives of thermal evolution temperature, gas adsorption, pore characteristics, total sulfur content, and the coal’s reducibility index. In addition, the degree of correlation for each factor was determined quantitatively using gray system theory to construct a generalized gray relational degree evaluation model. Finally, a high-pressure circulating pulsed alkali treatment technique was proposed to cope with the dangerous levels of hydrogen sulfide found in coal mines. The treatment technique was applied in the field. The results of the investigation on hydrogen sulfide formation show that the H2S in the #4 coal seam was generated by biological sulfate reduction. When the concentration of hydrogen sulfide increased from 0.8 ppm to 6 ppm, the ranges of the thermal evolution temperature, the adsorption constant, the Brunauer–Emmett–Teller (BET) specific surface area, the total sulfur content, and the reducibility index increased from 96°C to 113 °C, 28.8 to 36.2, 0.4125 m2•g–1 to 0.9864 m2•g–1, 0.21% to 0.88% and 3.1 to 8.5, respectively. The correlation coefficients of the main controlling factors, in descending order, were: reducibility index> adsorption constant> total sulfur content> thermal evolution temperature> BET specific surface area. The high-pressure circulating pulsed alkali treatment method tested can effectively control the high concentrations of hydrogen sulfide and prevent hydrogen sulfide related mine shutdowns.
Effect of delayed coking pressure on the yield and quality of middle and heavy distillates used as components of environmentally friendly marine fuels Energy Fuels (IF 3.024) Pub Date : 2018-12-04 Natalia K. Kondrasheva, Viacheslav A. Rudko, Dmitriy O. Kondrashev, Renat Gabdulkhakov, Ivan Derkunskii, Rostislav Konoplin
The paper includes the problem statement of obtaining environmentally friendly high-viscosity marine fuel, as well as a possible technological solution consisting in sequential oil processing in an atmospheric vacuum unit, processing of the vacuum residue with or without preliminary deasphalting in a delayed coking unit and subsequent compounding of light and heavy distillates from delayed coking unit with low-sulfur fractions. The research targets were tar and asphalt, which had been obtained from tar in the process of propane deasphalting. These residues were subjected to coking at 500°C and the pressure of 0.15 to 0.35 MPa. Physical properties and chemical composition, quantitative group hydrocarbon and trace-metal compositions (including vanadium and nickel) were determined for the feed and the obtained middle and heavy distillates. The possibility of applying the maximum amount of coking distillates to obtain environmentally friendly compositions of marine fuel with a sulfur content of up to 0.5% wt. was evaluated.
Coupling effects of super-critical CO2 sequestration in deep coal seam Energy Fuels (IF 3.024) Pub Date : 2018-12-03 Beining Zhang, Weiguo Liang, P. G. Ranjith, Zhigang Li, Chang Li, Dongsheng Hou
CO2 sequestration in deep un-minable coal seams is currently identified as a research hotspot to reduce CO2 emissions, due to the potential large-scale storage capacity and complicated physical and chemical reactions, especially for super-critical CO2 (scCO2). Hitherto, the interaction mechanisms between scCO2 and coal mass in situ conditions are still unclear. Therefore, the main objective of this study is to fully address the coupling effects of scCO2 sequestration on coal mass and provide a comprehensive evaluation of the interrelation of these variations. Five cycles of Helium and scCO2 injection were replicated on a sub-bituminous coal sample to investigate the permeability variation with scCO2 saturation time. Meanwhile, gas chromatography-mass spectrometry (GC-MS), gas chromatography (GC), fourier transform infrared spectroscopy (FTIR), proximate analysis and low-pressure-temperature nitrogen (N2) isotherm analyses were employed to characterize the transformation in coal mass. The test result shows that: (1) ScCO2 tends to mobilize a higher proportion of aliphatics than aromatics, and the concentration of the yielded hydrocarbons decreased with CO2 saturation time. (2) Carbonate and silicate cemented minerals were partly dissolved due to the formation of an acidic solution containing H2CO3. (3) The hydrocarbon extraction and mineral dissolution resulted in the corresponding FTIR absorbance bands being weakened and the volatile matter content and the ash content decreased by approximately 15% and 26%, respectively. (4) The coal pore volume and the Brunauer−Emmett−Teller (BET) surface area decreased by approximately 24% and 12%, respectively. (5) Due to CO2 adsorption and the reduction of Young’s modulus with saturation time, the volumetric strain increased from 0.23% to 3.26%, which led to coal permeability decreased from 0.042 md to 0.029 md. After analyzing the interrelation of these variations, the interaction mechanisms between scCO2 and coal mass in situ conditions were described and an overall negative effect on coal permeability were found.
MCMB Production from FCC Slurry Oil: Improving Performance through Supercritical Fluid Extraction Energy Fuels (IF 3.024) Pub Date : 2018-12-03 Dekai Zhang, Linzhou Zhang, Ying Yu, Liang Zhang, Zhiming Xu, Xuewen Sun, Suoqi Zhao
The utilization of fluid catalytic cracking (FCC) slurry oil is widely concerned in modern refineries due to its poor processability. The present study used FCC slurry oil (SLO) as feedstock to produce mesocarbon microbeads (MCMBs) according to its rich aromatic content. Supercritical fluid extraction technique was adopted to remove the undesirable components and thus improve the mesophase development performance. Three different alkanes were used as the supercritical fluids and the chemical composition of derived fractions (SFEO) was analyzed. Four stages of mesophase development were observed in the carbonization process. The results showed that heavier feedstock reacted faster and reached the coalescence stage earlier, forming a bulk mesophase. MCMBs with a smooth surface and good morphology were prepared from iso-butane derived SFEO at a reaction time of 3 h. The quality of bulk mesophase produced from SFEOs was significantly improved comparing to DQ SLO.
Removal of toluene as a tar analogue in a N2 carrier gas using a non-thermal plasma dielectric barrier discharge (DBD) reactor Energy Fuels (IF 3.024) Pub Date : 2018-12-03 faisal saleem, Kui (K.) Zhang, Adam P. Harvey
The role of N2 carrier gas towards the conversion of tar analogue (toluene) was studied in a non-thermal plasma dielectric barrier discharge (DBD) reactor. The parameters investigated were power (5-40 W), residence time (1.41-4.23 s), toluene concentration (20-82 g/Nm3) and wall temperature (ambient-400 oC). Almost complete removal (99 %) of toluene was observed at 40 W and 4.23 s. The main gaseous product was H2 with a maximum selectivity of 40 %. The other gaseous products were lighter hydrocarbons (5.5 %). The selectivity to these LHCs could be increased to 10 % by increasing the temperature to 400 oC. Introducing H2 to the N2 carrier gas at elevated temperatures opened up new reaction routes to enhance the selectivity to lower hydrocarbons (LHCs). The selectivity to methane reached 42 % at 35 % H2 at 400 oC, and the total selectivity to LHCs (lower hydrocarbons) reached 57 %.
Study on co-gasification of food waste char with biomass/coal char and their interaction mechanisms Energy Fuels (IF 3.024) Pub Date : 2018-12-03 Xiaopeng Zou, Lu Ding, Xin Gong
In this paper, the effects of gasification temperature and blending ratios on co-gasification reactivity of food waste char with sawdust/Shenfu coal char were studied via a thermogravimetric analyzer. Moreover, the relationship between synergy and char physic-chemical structure evolution was further studied using scanning electron microscopy equipped with energy dispersive X-ray analysis (SEM-EDS), N2 absorption and FT-Raman techniques. The results indicated that significant synergetic effect was found between food waste and Shenfu coal. The synergetic effect always occurred at mid-later reaction stage and was enhanced with the increase of carbon conversion. Meanwhile no synergy was found between food waste and sawdust. It is found that ash present in food waste (rich in Ca) transferred to the surface of Shenfu char without blocking the pore structure of Shenfu char. Moreover, the FT-Raman analysis showed that the food waste ash reacted with Shenfu char to form more active sites, resulting in higher gasification reactivity. Whereas, no ash exchange was found during co-gasification of food waste with sawdust.
Effects of a Quaternary Ammonium Salt on the Growth, Wettability, and Agglomeration of Structure II Hydrate Crystals Energy Fuels (IF 3.024) Pub Date : 2018-12-03 H. Delroisse, J.-P. Torré, C. Dicharry
This work studied the effects of a water-soluble quaternary ammonium salt (called DA 50) on the growth, wettability, and agglomeration of cyclopentane (CP) hydrate crystals and methane (CH4)/propane (C3H8) hydrate crystals. The impact on these properties of adding 4 wt % NaCl to the DA 50 solution was also investigated. The hydrates were formed from water/CP, water/(CP + n-octane (n-C8)), and water/(CP + n-dodecane (n-C12)) mixtures at atmospheric pressure and from a water/n-C8/(CH4 + C3H8) mixture under pressure (about 67 bar). Experiments were performed at a subcooling of 6 °C in the case of the CP hydrates and 9–10 °C in the case of the CH4/C3H8 hydrates. In both hydrate systems, adding NaCl to the surfactant solution of 0.1 or 1 wt % DA 50 led to the formation of individual oil-wettable pyramidal crystals. Without salt, the hydrate formed a water-wettable shell that covered the water/oil interface just as the system without surfactant did. The antiagglomeration performance of the 1 wt % DA 50 solution was evaluated by performing torque measurements in an agitated batch reactor at a water cut of 30 vol %. Without NaCl, torque increased with the amount of CP hydrates. The system formed a nonflowable jelly-like phase, with water as the continuous phase, until a phase inversion occurred. From there on torque significantly decreased and the system became a flowable dispersion of large hydrate particles (∼700 μm) in the CP phase. With 4 wt % NaCl, the system consisted of small (∼70 μm) hydrate particles dispersed in the CP phase and the torque signal remained constant throughout the hydrate crystallization process. The torque profiles obtained at concentrations of 0 or 4 wt % NaCl for the CP hydrates and the CH4/C3H8 hydrates were similar, suggesting analogous states for both systems. For both hydrate systems, adding NaCl to the DA 50 solution led to the formation of oil-wettable hydrates and drastically improved the antiagglomeration performance of the surfactant molecules, revealing a correlation between the formation of individual crystals and the antiagglomeration performance of the surfactant. The similarity between the growth patterns and shapes of the CP–hydrate crystals and the CH4/C3H8–hydrate crystals confirmed that CP hydrates are an interesting model for evaluating the antiagglomeration performance of surfactants.
Pyrolysis of Lignin in Gas-Phase Isothermal and cw-CO2 Laser Powered Non-Isothermal Reactors Energy Fuels (IF 3.024) Pub Date : 2018-12-03 Lavrent Khachatryan, Mohamad Barekati-Goudarzi, David Kekejian, Gustavo Aguilar, Rubik Asatryan, George G. Stanley, Dorin Boldor
Pyrolysis of lignin in the gas-phase using “wall-less” and cw-IR CO2 laser powered homogeneous pyrolysis (LPHP) non-isothermal and continuous droplet evaporation (CDE) isothermal reactors has been performed. Hydrolytic lignin was dissolved in an acetone/water (9:1) mixture and dispersed into LPHP and CDE reactors using a constant output atomizing device and a syringe pump, respectively. Large differences in gas phase depolymerization of lignin have been seen in both reactors. The temperature distribution in the LPHP reactor was evaluated by thermocouple measurements and validated by the method of “chemical thermometer” and COMSOL Multiphysics simulations. The gas phase delivery of lignin into the hot zone of the LPHP reactor under “wall-less” conditions led to the breakdown of lignin into paramagnetic fragments that deposited onto the cell walls, which were studied by electron paramagnetic resonance spectroscopy. Phenolics were not detected at all in the LPHP reactor. However, major phenolics (phenol(s), guaiacol(s), syringol(s)) were detected in the CDE reactor. At laser powers higher than 20 W and a high initial concentration of dispersed lignin (5 g/L), an intensification of demethoxylation reactions of phenolics by concomitant alkylation of aromatic rings along with the expulsion of CO from phenoxy rings (to account for formation of indenes and naphtalenes) was achieved in the LPHP reactor when a prepyrolyzed mixture from the CDE reactor entered the LPHP reactor. The yields of qualified biofuel products such as styrene, different alkyl benzenes, and surrogate fuels of diesel such as indene, 1,2-dihydro naphthalene, naphthalene, and other derivatives were detected in the LPHP reactor with decreasing amounts of phenolics. These results represent valuable observations about the primary mechanism of lignin depolymerization.
Biomass fast pyrolysis using a novel micro-particle micro-reactor approach: Effect of particles size, biomass type and temperature Energy Fuels (IF 3.024) Pub Date : 2018-12-03 Ali Zolghadr, Joseph James Biernacki, Ronald J. Moore
Biomass fast pyrolysis is emerging as a front-running approach for the generation of renewable chemical and fuel resources. The pyrolysis temperature, solid and gas phase residence times, and biomass particle size and type have a substantial impact on char, oil and gas yields. A laboratory-scale fast pyrolysis technique was demonstrated using manufactured biomass microspheres. A unique single-particle (~10µg) micro-reactor technology coupled to a millisecond response flame ionization detector (fast-FID) was used to investigate the effects of relevant particle and process parameters and to capture the dynamic of real-time micro-scale single-particle pyrolysis for the first time. The manufactured biomass microspheres were produced by spray drying finely milled microcrystalline cellulose, switchgrass (Panicum virgatum) and tall fescue straw (Festuca arundinacea) flour.
Metal Oxide Promoted Hydrodeoxygenation Activity of Platinum in Pt-MOx/Al2O3 Catalysts for Green Diesel Production Energy Fuels (IF 3.024) Pub Date : 2018-12-01 Sagar Janampelli, Srinivas Darbha
Catalytic deoxygenation of fatty acids into renewable hydrocarbons (green diesel) was investigated over 4Pt-8MOx/Al2O3 (M = Mo, Re, W and Sn) catalysts prepared by wet impregnation method. Platinum deposited on MOx modified -Al2O3 showed higher catalytic hydrodeoxygenation activity than "neat" Pt/Al2O3 catalyst. The promotional effect of metal oxides (MOx) decreased in the order: MoOx > ReOx > WOx > SnOx. Characterization studies revealed that metal oxides affect the textural and electronic properties of Pt. Supported Pt facilitated reduction of these metal oxides. Synergy and electronic contact between Pt and MOx determined the catalytic deoxygenation performance. Fatty acid conversion increased with increasing metallic nature (decreasing binding energy) of Pt. Hydrodeoxygenation product selectivity correlated with the extent of metal oxide reduction. Among the catalysts, 4Pt-8MoOx/Al2O3 had the optimum dispersion and electron rich Pt and reduced Mo5+ species enabling quantitative conversion of oleic acid with 93.5% octadecane selectivity at a temperature as low as 220 ᵒC and 20 bar hydrogen pressure. Metal oxide switched the mechanism of deoxygenation from decarbonylation/decarboxylation to hydrodeoxygenation. Fatty acids, methyl oleate and vegetable oil were deoxygenated with equal efficiency over this catalyst. Catalysts were reusable in recycling studies only at higher temperature (320 °C) than at lower temperature (260 °C), perhaps due to strong sticking of reactant molecules at lower temperature on the catalyst surface than at higher temperature.
Carrying Capacity and Gas Flow Path Mechanism of a Novel Multistage Air Reactor for Chemical Looping Combustion Energy Fuels (IF 3.024) Pub Date : 2018-11-30 Yali Shao, Xiaojia Wang, Baosheng Jin, Yong Zhang, Zhiwei Kong, Xudong Wang, Zhaoyang Jin
Prediction of Adsorption Isotherms of Multicomponent Gas Mixtures in Tight Porous Media by the Oil–Gas-Adsorption Three-Phase Vacancy Solution Model Energy Fuels (IF 3.024) Pub Date : 2018-11-30 Yizhong Zhang, Shanshan Yao, Maolin Zhang, Xiang Zhou, Haiyan Mei, Fanhua Zeng
For unconventional reservoirs, the effect of adsorption on phase equilibrium cannot be neglected because the process occurs in extremely tight porous media. This work focuses on the adsorption prediction of multicomponent mixture systems in tight porous media with the oil–gas-adsorption three-phase equilibrium model to a gas sample in the literature. The revisited vacancy solution model of adsorption by Bhatia and Ding is introduced to study the adsorption behaviors of the mixture. The gas and adsorbed phases are assumed to be the solutions of adsorbates with a hypothetical solvent called “vacancy”, and the vacancy is treated as an additional component engaged in the phase equilibrium in this theory. Instead of using parameters extracted from the multicomponent adsorption data, this method takes advantage because it accurately predicts the gas mixture adsorption equilibrium with consideration of non-ideal behavior in the adsorbed phase from pure gas adsorption isotherms over wide ranges of conditions, which could be efficient in terms of cost and time. It can explain the competitive adsorption phenomenon, which is proven during the adsorption process of the gas mixture. The experimental data in the literature of CH4–C2H6 binary gas mixtures of different compositions with a pressure ranging from 0 to 125 bar under the temperatures of 40, 50, and 60 °C are restudied in this work. The prediction results are compared to two other methods, including the extended Langmuir model and the multicomponent potential theory. This method shows an improved precision with less than 5% mean absolute percentage error in all cases. In addition to predications of desorption for the depletion process, the vacancy solution model has the potential in future work to give simulations for other production operations, such as CO2 or N2 injection for the displacement of hydrocarbons in shales.
Molecular Simulation of Carbon Dioxide and Methane Adsorption in Shale Organic Nanopores Energy Fuels (IF 3.024) Pub Date : 2018-11-30 Kecheng Zeng, Peixue Jiang, Zengmin Lun, Ruina Xu
Using carbon dioxide as a displacing fluid to enhance shale gas recovery is a promising technique given its potential for significant contributions to both unconventional resource development and CO2 geological sequestration. The adsorption capacity of CO2 in nanoscale shale organic pores is the key issue to evaluate the feasibility of CO2-enhanced shale gas recovery technology. However, as a result of the complex organic component of the solid surface, the fluid–solid interaction between the confined fluid and the solid surface, and the intermolecular interaction between the confined fluids, the adsorption behavior of CO2 in the shale is not clear. In this work, shale organic nanopores with different geometries (slit pore and cylindrical pore) and different sizes (1, 2, and 4 nm) are constructed using molecular dynamics and Monte Carlo methods. Isothermal adsorption of CO2 and methane as single components and competitive adsorption of a CO2–methane binary mixture are simulated in a nanoscale methane/CO2/organic matter system. The density profile and distribution contour indicate that CO2 adsorption in shale organic mesopores does not occur via monolayer adsorption. Considering the inadaptability of the Langmuir model to analyze the CO2 adsorption curve, a modified Brunauer–Emmett–Teller (BET) model is applied to describe and fit the data for the CO2 and methane adsorption amount, with the parameters in the modified BET model used to characterize the adsorption capacity and affinity of the fluid. The maximum adsorption amount, characteristic pressure, and selectivity parameter of CO2, methane, and a binary mixture indicate that the adsorption capacity and affinity of CO2 are stronger than those of methane under reservoir pressure, which provides useful support for enhancing shale gas recovery by injecting CO2.
Experimental Study on the Bubble Formation Mechanism during the Sintering of Coal and Biomass Ash Blends Energy Fuels (IF 3.024) Pub Date : 2018-11-30 Hao Zhou, Dan Liu, Weichen Ma
This paper presents an experimental study on bubble formation in the process of sintering of Zhundong coal and corn stalk (CS) ash blends in a horizontal chamber furnace. The effect of the blend ratio of biomass ash was investigated. Bubble parameters, such as number, area, and porosity, were measured on the basis of a metalloscope equipped with a charge-coupled device camera and digital image processing technique. After sintering experiments, ash and condensed matter in the bubbles were sampled and analyzed by X-ray diffraction. In addition, a chemical equilibrium calculation was conducted to reveal the influence of biomass ash on the formation of bubbles. The experimental results show that a 50% CS blend has the greatest melting degree and the formation time of bubbles is earlier than other cases, while a low ratio of CS ash has limited influence on bubble formation and mineral composition. The formation mechanism of bubbles is proposed on the basis of the results. The condensed matter in the bubbles mainly contains NaCl, CaSO4, and KCl. The results indicate that chlorine promotes the transformation of alkali metals to gaseous phase. The chemical equilibrium calculation verified the experimental results.
New Cu2O-SiO2 Composite Aerogel-like Desulfurization Adsorbents with Different Molar Ratio of Si/Cu Based on π-Complexation Energy Fuels (IF 3.024) Pub Date : 2018-11-30 Shaobo Liu, Bo Zhang, Zhanqi Bai, Feifan Chen, Fang Xie, Jinbing Zhou, Yongkang Lu, Guangwu Miao, Jiamin Jin, Zekai Zhang
Molecular Dynamics Study on Aggregating Behavior of Asphaltene and Resin in Emulsified Heavy Oil Droplets with Sodium Dodecyl Sulfate Energy Fuels (IF 3.024) Pub Date : 2018-11-30 Shenghan Song, Heng Zhang, Lixin Sun, Jing Shi, Xulong Cao, Shiling Yuan
The aggregates of asphaltene and resin molecules play an important role in stabilizing heavy crude oil. Although many experiments are applied to investigate the complex aggregating structure of asphaltene and resin molecules in heavy crude oil, those microstructure and properties are still not clear at the molecular level. As another auxiliary tool, molecular dynamics (MD) simulation can be used to simulate the behavior of asphaltene and resin in the heavy oil droplet or emulsified oil droplet. The simulation results showed the following: (i) Asphaltene and resin molecules can form a netlike structure in heavy oil through face-to-face or edge-to-face stacking interaction, and the aggregating structure is considered to be the main reason that heavy crude oil has high viscosity. (ii) When surfactant molecules were added to the heavy oil phase, the asphaltene molecules moved to the center of emulsified oil droplet from the oil/water interface. The adsorption of surfactant molecules at the interface resulted in an increase in the hydrophilic surface area of the oil droplet. We think that the changed hydrophilicity of emulsified oil droplet is the key to the viscosity reduction of heavy oil. (iii) The steered MD simulation can prove that the interaction among asphaltene and resin molecules becomes fragile in emulsified heavy oil droplet, and it indicates that the added surfactant molecules are beneficial to the viscosity reduction in crude oil.
Single-Step Synthesis of Nitrogen-Doped Porous Carbons for CO2 Capture by Low-Temperature Sodium Amide Activation of Petroleum Coke Energy Fuels (IF 3.024) Pub Date : 2018-11-30 Linli Rao, Shenfang Liu, Jiao Chen, Linlin Wang, Liying An, Pupu Yang, Xin Hu
In this work, highly efficient nitrogen-doped porous carbonaceous CO2 sorbents were synthesized by sodium amide activation of petroleum coke at a temperature range of 400–500 °C. The as-obtained sorbents exhibit an excellent CO2 uptake of 3.84 mmol/g (25 °C) and 5.93 mmol/g (0 °C) under atmospheric pressure. It is found that in addition to the two well-accepted factors, i.e., narrow micropore volume and nitrogen content, the pore size and pore size distribution also exhibit important effects on CO2 uptake under ambient condition for these adsorbents. Furthermore, these petroleum-coke-derived nitrogen-enriched carbonaceous sorbents also exhibit other merits such as high selectivity of CO2 over N2, excellent recyclability, fast adsorption kinetics, suitable heat of adsorption, and excellent dynamic CO2 uptake. This paper offers additional insight and useful information in preparing highly efficient nitrogen-doped porous carbonaceous CO2 adsorbents.
Carbon dioxide/brine, nitrogen/brine and oil/brine wettability of montmorillonite, illite and kaolinite at elevated pressure and temperature Energy Fuels (IF 3.024) Pub Date : 2018-12-01 Cut Aja Fauziah, Ahmed Zarzor Al-Yaseri, Roman Beloborodov, Mohammed AQ Siddiqui, Maxim Lebedev, Drew Francis Parsons, Hamid Roshan, Ahmed Barifcani, Prof. Stefan Iglauer
The montmorillonite, illite and kaolinite wettability for CO2/brine, nitrogen/brine and nitrogen/oil systems was systematically measured at various pressures (5 MPa, 10 MPa, 15 MPa and 20 MPa) and temperatures (305 Kand 333 K). The zeta potential of each clay mineral was also measured to investigate its link to the macroscopic contact angle. The results show that both advancing and receding water contact angles increase with an increase in pressure;however,they are insensitive/slightly reduced byincreasing temperature. Furthermore, we point out that decreasing the surface charge densitypromotes oil-wet surfaceswhileincreasingthe surface charge density increases water-wetness. Moreover, increasing pressure causes the clay surface to be more hydrophobic. Finally, we conclude that montmorillonite is strongly oil-wet, kaolinite and illite, however, are strongly water-wet at typical storage conditions (high pressure, elevated temperature).
Study of Novel Aromatic Aminomethylenephosphonates as Oilfield Scale Inhibitors Energy Fuels (IF 3.024) Pub Date : 2018-12-01 Mohamed F. Mady, Synnøve Fevang, Malcolm A. Kelland
Non-polymeric phosphonates are well-known scale inhibitors in the upstream oil and gas industry because they afford several advantages over other classes of inhibitors. But few of these phosphonates show good environmental properties as well as good thermal stability for high temperature squeeze applications. Given the known high seawater biodegradability of benzoic acid, we have synthesized and tested several easily accessible monoaromatic phosphonates. The tests include dynamic tube blocking experiments for both calcite and barite scaling, thermal stability, calcium compatibility and seawater biodegradation according to the OECD306 protocol. The new aromatic inhibitors were compared to known aminophosphonate scale inhibitors including the aromatic amino acid derivative, phenylalanine diaminomethylenediphosphonate (PADMP). The results indicate that improved performance can be obtained together with good thermal stability for the phenolic derivatives but too much aromatic ring-substitutions leads to lower biodegradation.
Comparative Study of Resins and Asphaltenes of Heavy Oils as Sources for Obtaining Pure Vanadyl Porphyrins by Sulfocationite-based Chromatographic Method Energy Fuels (IF 3.024) Pub Date : 2018-11-30 Nikolay Alexandrovich Mironov, Guzalia Rashidovna Abilova, Yulia Yurevna Borisova, Elvira Gabidullovna Tazeeva, Dmitry Valerevich Milordov, Svetlana Gabidullinovna Yakubova, Makhmut Renatovich Yakubov
The resins and asphaltenes of three heavy oils differing in origin (Permian and Carboniferous) and vanadium content (0.025 – 0.165 wt. %) have been studied as sources for isolation of spectrally pure vanadyl porphyrins by sulfocationite-based chromatographic method developed by us recently. This method consists of removing the low polar non-porphyrin components from the resins or DMF extract of asphaltenes on SiO2-column followed by chromatographic isolation of vanadyl porphyrins on the sulfocationite. The asphaltenes were revealed to be more promising source of vanadyl porphyrins because they possess ≥5 times higher content of vanadium, provide better accumulation of vanadyl porphyrins during deposition extraction by N,N-dimethylformamide, and are less contaminated by low polar non-porphyrin compounds capable of co-eluting with vanadyl porphyrins through the sulfocationite column. According to matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy, DPEP vanadyl porphyrins were found to be the most abundant type for all studied samples (34.1 – 54.5%). Rhodo vanadyl porphyrins belong to minor components (3.3 – 8.7% for each subtype) while Etio and Di-DPEP types take intermediate position (9.8 – 28.7%). The resins and asphaltenes of the same oil showed significant difference in the group composition of purified vanadyl porphyrins. For the resins, a ~1.3-fold decreased content of DPEP vanadyl porphyrins was found, which was compensated by a ~1.5- and/or ~1.8-fold increase in the content of Etio and Rhodo vanadyl porphyrins, respectively. However, this change in the composition of vanadyl porphyrins is not accompanied by a notable change of their average molecular weight despite increased concentration of more substituted (i.e., more hydrophobic) vanadyl porphyrins could be expected for less polar resins. This fact was interpreted in favor of association of vanadyl porphyrins with non-porphyrin components of the oil.
Co-pyrolysis behavior and char structure evolution of raw/torrefied rice straw and coal blends Energy Fuels (IF 3.024) Pub Date : 2018-11-30 Qing He, Qinghua Guo, Lu Ding, Yan Gong, Juntao Wei, Guangsuo Yu
Combination of biomass and coal for energy production is conducive to sustainable development of society and clean-energy future. This study investigates co-pyrolysis behavior of raw/torrefied rice straw and coal blends. Mild-torrefaction (250 °C) and severe-torrefaction (300 °C) were taken into consideration. Samples of five mixing ratios were tested by thermogravimetric analyzer and the resulting chars were characterized by Raman spectroscopy and SEM-EDS. The results show that co-pyrolysis had little effect on char yields. Decomposition rate curves showed two distinct peaks for raw/mild-torrefied rice straw and coal blends, and the reaction rate was enhanced below 380 °C. However, only one peak appeared for severe-torrefied rice straw blending with coal. During co-pyrolysis, the secondary pyrolysis of coal around 700 °C was inhibited, and the graphitization degree of biomass char increased while the crystalline structure of coal char was poorly organized. The activation energy of mixtures also changed in different pyrolysis stages.
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