显示样式:     当前期刊: Fuel    加入关注       排序: 导出
我的关注
我的收藏
您暂时未登录!
登录
  • 更新日期:2018-06-22
  • Mechanisms of mercury transformation over α-Fe2O3(0 0 1) in the presence of HCl and/or H2S
    Fuel (IF 4.601) Pub Date : 2018-06-20
    Yu Chen, Xin Guo, Fan Wu, Yu Huang, Zhanchi Yin
    更新日期:2018-06-22
  • Effect of diesel late-injection on combustion and emissions characteristics of diesel/methanol dual fuel engine
    Fuel (IF 4.601) Pub Date : 2018-06-20
    Taoyang Wu, Anren Yao, Chunde Yao, Wang Pan, Hongyuan Wei, Chao Chen, Jian Gao

    The late-injection strategy (close after main-injection) of common-rail diesel engine is capable of enhancing combustion turbulence and reducing particulate matter (PM) emissions. In this work, experimental study was performed to investigate the effect of diesel late-injection on combustion and emissions characteristics of diesel/methanol dual fuel (DMDF) engine. The experiments were carried out at a constant engine speed of 1340 rpm and a medium load of 1.0 MPa brake mean effective pressure (BMEP) with various methanol substitution ratio (MSR) on a common rail DMDF engine. The results reveal that higher MSR caused simultaneous decrease of nitric oxides (NOx) and accumulation mode PM emissions in spite of late-injection strategy. In particular, an augment of up to 12.8% in nucleation mode particle number (PN) was observed as MSR increased from 15% to 50%. A small late-injection of diesel (<7.5 mg/cycle) had little impact on in-cylinder pressure and heat release rate (HRR). However, enhanced or retarded late-injection led to a decline in peak gas mean temperature (GMT) but an increase in later combustion temperature. With late-injection quantity (LIQ) increased from 1.5 mg/cycle to 7.5 mg/cycle, both NOx and accumulation mode PM decreased. Meanwhile, nucleation mode PM was almost unchanged and even rebounded slightly with overmuch LIQ (7.5 mg/cycle) in DMDF mode. Retarded late-injection led to a continuous reduction of 12.9% at most in NOx emissions in DMDF operation. As the interval between main-late injections (MLII) increased from 800 μs to 1200 μs, a trade-off relation appeared between nucleation mode and accumulation mode particles due to the mutual transformation of them. Furthermore, too delayed late-injection (MLII > 1200 μs) induced a simultaneous increase of particles with different size.

    更新日期:2018-06-22
  • Water catalyzed pyrolysis of oxygen functional groups of coal: A density functional theory investigation
    Fuel (IF 4.601) Pub Date : 2018-06-20
    Sathish Kumar Mudedla, Choutipalli Venkata Surya Kumar, A. Suresh, Prathap Baskar, Pratik Swarup Dash, Venkatesan Subramanian

    The pyrolysis mechanism of carboxylic and hydroxyl groups which are present in the coal has been investigated with the help of density functional theory calculations. The role of water in the pyrolysis reaction mechanisms has also been investigated by the calculation of activation energy barriers. The activation energy barriers for the water mediated reactions are less when compared to thermal pyrolysis process. The results show the significant decrease in the energy barriers for decarboxylation reactions than the hydroxyl groups in the presence of water. Therefore, water can significantly decrease the oxygen content in the non-coking coals with high content of carboxylic groups.

    更新日期:2018-06-22
  • Preparation and characteristic of the fly ash cenospheres/mullite composite for high-temperature application
    Fuel (IF 4.601) Pub Date : 2018-06-20
    Sue Ren, Xin Tao, Xiqing Xu, Anran Guo, Jiachen Liu, Jinpeng Fan, Jingran Ge, Daining Fang, Jun Liang
    更新日期:2018-06-22
  • Numerical simulation of premixed combustion using the modified dynamic thickened flame model coupled with multi-step reaction mechanism
    Fuel (IF 4.601) Pub Date : 2018-06-21
    Shilong Guo, Jinhua Wang, Xutao Wei, Senbin Yu, Meng Zhang, Zuohua Huang

    Thickened flame (TF) model is one of the effective methods to resolve the flame front in turbulent premixed combustion modeling. The multi-step reaction mechanism is becoming increasingly important for combustion simulations such as pollutant formation, ignition and extinction. The effect of TF model on flame structures when coupling with multi-step reaction mechanism was investigated. The simulation results show that, no matter in laminar or turbulent condition, the global TF model coupling with multi-step reaction mechanism results in an incomplete combustion, which is mainly due to the enhanced species diffusion. Although Durand and Polifke’s dynamic thickened flame (DTF) sensor performs well for predicting laminar flame structure when coupling with multi-step reaction mechanism, it underestimates the effective thickening factor. In turbulent premixed flame simulation, the underestimated thickening factor leads to a faster local fuel consumption speed because of the over-predicted sub-grid flame wrinkling factor. A modified DTF sensor suitable for multi-step reaction mechanism is proposed. This sensor using the hyperbolic tangent function of progress variable to calculate thickening factor dynamically. It ensures that both the preheated and reaction zones are thickened effectively. The sub-grid wrinkling factor is hence estimated corresponding to the calculated flame thickness. Results of 1D laminar and 3D turbulent flame show that this method performs well for predicting both burned gas temperature and species concentration in burnt gas, which is important for predicting emissions.

    更新日期:2018-06-22
  • Simulations on recoverability performances for a coalbed methane field in SE edge of Ordos basin, China
    Fuel (IF 4.601) Pub Date : 2018-06-21
    Mingjun Zou, Simin Wei, Zhiquan Huang, Xiaochun Lv, Biao Guo

    This paper mainly studies the recoverability performances for a coalbed methane (CBM) field located in the southeastern edge of the Ordos basin of China. Geological models are established, and drainage performances for four typical wells are described in detail. Single well simulations for the four wells are conducted to check accuracies of parameters and predict well drainage performances, and optimizations of well spaces are simulated to determine the most suitable well space. Results indicate that the reservoir parameters used in this study are quite accurate, and the well space of 350 × 300 m is most suitable in this area. Furthermore, the fifteen years’ field simulation under the well space of 350 × 300 m is conducted, which shows that the well number, average production and cumulative production are 1944, 7.01 × 108 m3/d and 105.22 × 108 m3, respectively. To validate the well space used in this study, analyses of recoverability and economic profit are conducted, both of which demonstrate that the well space of 350 × 300 m is most suitable in this area and can bring a stable drainage performance for a long time and get a high gas production.

    更新日期:2018-06-22
  • Geochemical behavior of hazardous volatile elements in coals with different geological origin during combustion
    Fuel (IF 4.601) Pub Date : 2018-06-21
    Guangqing Hu, Guijian Liu, Dun Wu, Biao Fu

    The geochemical behaviors of hazardous elements in the combustion process of Chinese coals with different geological origins at different temperatures were studied. The analyzed coal samples were placed in a fixed bed reactor with a quartz tube and heated to six desired temperature points, from 400 °C to 900 °C with 100 °C for each interval. The mineral morphology and composition of coal and coal ash were determined by X-ray fluorescence (XRF), scanning electron microscope-X-ray Energy Dispersive Spectrom (SEM-EDS) and X-ray powder diffraction techniques (XRD). Sequential chemical extraction procedure was used to describe the modes of occurrence of selected hazardous elements in coal. The content of arsenic (As) in coal and coal ash was analyzed by inductively coupled plasma mass spectrometry (ICP-MS), and the content of selenium (Se) and mercury (Hg) in coal ash was analyzed by atomic emission spectrometry (AES) and atomic fluorescence spectrometry (AFS). The volatile characteristics of As, Se and Hg in coal were studied by thermogravimetry (TG). The results show that: 1) the mineral phases of Liuzhuang (LZ) and Huajiahu (HJH) coal samples are mainly composed of clay minerals and silicate minerals and the contents of As, Se and Hg were closely related to the organic matter and inorganic mineral in coal; 2) As mainly exists in organic matter and Se, Hg mainly exists in silicate minerals. The organic As in coal is closely related to the low-rank, low ash content and low As content of coal. The modes of occurrence of Se and Hg may be related to the low element content, low sulfide content in coal and stable sedimentary environment; 3) the relationship between volatilization rate (Vr) of As, Se and Hg elements and combustion temperature is the closest. The differences of Vr of As, Se and Hg elements in coal of different geological origin are mainly related to elements concentration and coal quality; 4) at different heating rates, the Vr curves of As, Se and Hg elements have the characteristics of “S” type, logarithmic type and linear type, respectively; The Initial stable temperature of Vr is different under the influence of element geochemical characteristics. The volatility of As reaches the maximum at 800 °C, and Se and Hg reach the maximum at 700 °C and 600 °C, respectively; 5) The heating rate and the difference of coal quality under different geological origin are important factors affecting the Vr of As, Se and Hg. The maximum weight loss temperature (TP) can be used as an important index to reflect the influence of coal quality and heating rate on the Vr of hazardous elements (As, Se and Hg).

    更新日期:2018-06-22
  • Investigations on the effects of premixed ethanol/air atmosphere on combustion characteristics of n-heptane spray in a combustion vessel
    Fuel (IF 4.601) Pub Date : 2018-06-19
    Shijun Dong, Zhaowen Wang, Can Yang, Biao Ou, Liang Qiu, Fumin Pan, Xiaobei Cheng

    In ethanol/diesel dual-fuel engines, premixed ethanol/air atmosphere could affect the ignition delay of diesel spray as well as the following soot formation. In this paper, a reduced mechanism describing the chemistry of ethanol and n-heptane was composed and validated with various experimental data. Based on this mechanism, simulations were conducted to investigate the combustion characteristics of n-heptane spray under premixed ethanol/air atmosphere in a combustion vessel. The effects of equivalence ratio of premixed ethanol/air atmosphere, ambient temperature and charge cooling effect of ethanol vaporization were investigated. Under premixed ethanol/air atmosphere, the results showed that high temperature ignition first occurred in the regions with mixture near stoichiometric ratio, rather than regions with largest n-heptane content (i.e. highest fuel reactivity). This is mainly because the vaporization of direct injected n-heptane decreased the gas temperature and consequently restricted the low temperature reaction. While the equivalence ratio of premixed ethanol/air atmosphere was further increased, the mixture near stoichiometric ratio exhibited lower fuel reactivity, which consequently resulted in prolonged ignition delay. It was also found that premixed ethanol could inhibit the soot formation of n-heptane spray under low ambient temperatures while contributed to significantly increased soot emission under high ambient temperatures. Moreover, the simulated results showed that the cooling effect of ethanol vaporization also played an important role in soot reduction of dual-fuel combustion.

    更新日期:2018-06-20
  • Impact of hydrothermal carbonization conditions on the formation of hydrochars and secondary chars from the organic fraction of municipal solid waste
    Fuel (IF 4.601) Pub Date : 2018-06-19
    Michela Lucian, Maurizio Volpe, Lihui Gao, Giovanni Piro, Jillian L. Goldfarb, Luca Fiori

    Hydrothermal carbonization of the organic fraction of municipal solid waste (OFMSW) could mitigate landfill issues while providing a sustainable solid fuel source. This paper demonstrates the impact of processing conditions on the formation and composition of hydrochars and secondary char of OFMSW. Harsher conditions (higher temperatures, longer residence times) decrease generally the solid yield while increasing the higher heating value (HHV), fixed carbon, and elemental carbon. Energy yields upwards of 80% can be obtained at both intermediate and high temperatures (220 and 260–280 °C), but the thermal stability and reactivity of the intermediate hydrochars suggest the formation of a reactive secondary char that condenses on the surface of the primary hydrochar. This secondary char is extractable with organic solvents and is comprised predominantly of organic acids, furfurals and phenols, which peak at 220 and 240 °C and decrease at higher carbonization conditions. The HHVs of secondary char are significantly higher than those of primary char.

    更新日期:2018-06-20
  • Effects of hydrogen and initial pressure on flame characteristics and explosion pressure of methane/hydrogen fuels
    Fuel (IF 4.601) Pub Date : 2018-06-19
    Yanchao Li, Mingshu Bi, Bei Li, Yonghao Zhou, Wei Gao

    Methane/hydrogen fuels are widely applied in the internal combustion engine and gas turbine due to enhanced laminar burning velocity and extended flammability limits. In order to ensure energy utilization in safety, the flame characteristics and explosion pressure in the lean, stoichiometric and rich mixture are investigated systematically by varying hydrogen addition and initial pressure. In the lean and stoichiometric mixture, effects of the diffusional-thermal and hydrodynamic instability on flame destabilization are enhanced with hydrogen addition. As initial pressure increase, the diffusional-thermal instability has a limited effect on flame destabilization while effects of the hydrodynamic instability continue to enhance. In the rich mixture, effects of the diffusional-thermal instability on the flame stabilization and effects of the hydrodynamic instability on the flame destabilization enhance significantly with hydrogen addition. As initial pressure increase, effects of the diffusional-thermal instability on the flame stabilization are very limited and effects of the hydrodynamic instability on the flame destabilization are enhanced. The variation in maximum explosion pressure could be neglected with hydrogen addition due to decreasing heat loss, and maximum pressure rise rate increases with hydrogen addition. Besides, explosion pressure evolution could be evaluated accurately by considering the flame instabilities. And by varying equivalence ratio, hydrogen addition and initial pressure, the most enhancing and inhibiting reactions to laminar flame velocity are H + O2 = O + OH and H + CH3(+M) = CH4(+M), respectively.

    更新日期:2018-06-20
  • Deactivation kinetics with activity coefficient of the methanol to aromatics process over modified ZSM-5
    Fuel (IF 4.601) Pub Date : 2018-06-19
    Na Li, Chen Meng, Dianhua Liu

    A lumped kinetic model for methanol to aromatics (MTA) process was investigated using modified ZSM-5 industrialized catalyst. The deactivation kinetic behavior of MTA was studied by developing a 5-lump kinetic model to describe the product distributions. The feedstock and products are divided into five lumps by simplifying reaction network, including oxygenates (methanol and dimethyl ether), C1 (CO, CO2, CH4 and H2), aliphatic hydrocarbons, light aromatics (C6-C8) and heavy aromatics (C9+). The catalytic activity was reflected by activity coefficient a. The deactivation model kinetic parameters were estimated using simplex and nonlinear least squares methods. This model can be used to predict key products and their compositions of MTA industrial process.

    更新日期:2018-06-20
  • The use of numerical simulation to investigate the enhanced Eagle Ford shale gas condensate well recovery using cyclic CO2 injection method with nano-pore effect
    Fuel (IF 4.601) Pub Date : 2018-06-17
    Tao Wan, Zongjie Mu

    The huge reserves of Eagle Ford shale gas condensate reservoirs have drawn great attention. The well productivity analysis indicates that the leading Eagle Ford is in reservoir decline stage. Condensate banking effect induces severer adverse effect on ultra-low permeability reservoirs and shale gas production than conventional reservoirs. The objective of this paper is to investigate the effect of CO2 huff-n-puff injection on mitigating condensate accumulation surrounding the induced fractures. The nano-pore confinement effect on condensate and gas production performance is considered. The nano-meter scale of shale condensate plays exhibit different phase behavior than conventional condensate reservoirs. The influence of nano-pore confinement on liquid phase behavior in shales is similar to adding CO2 in admixture with reservoir fluids, which acts to suppress the phase envelope. The interaction of CO2 injection with reservoir oil at molecular scale was discussed. Two scenarios including a lean gas condensate and rich gas condensate were compared in order to study the CO2 huff-n-puff performance with different reservoir fluids. The simulation results indicated that CO2 is more favorable in improving the rich condensate recovery. Removal of condensate accumulation in rich condensate Eagle Ford shale reservoirs by CO2 huff-n-puff injection results in substantial recovery increment in comparison with the pressure depletion scheme. This paper focuses on studying the influences of nano-pore walls on CO2 injection phase behavior in shale gas-condensate reservoirs.

    更新日期:2018-06-19
  • Determination of redox pathways of supported bimetallic oxygen carriers in a methane fuelled chemical looping combustion system
    Fuel (IF 4.601) Pub Date : 2018-06-17
    Mansour Mohammedramadan Tijani, Aqsha Aqsha, Ningyu Yu, Nader Mahinpey
    更新日期:2018-06-19
  • Description of kerosene / air combustion with Hybrid Transported-Tabulated Chemistry
    Fuel (IF 4.601) Pub Date : 2018-06-18
    Bastien Duboc, Guillaume Ribert, Pascale Domingo

    A strategy to introduce the detailed chemistry of kerosene-air combustion into simulations of flames is reported. Despite the rise in computer power achieved during the last decade, simulations of combustion chambers using detailed chemistry mechanisms are still not possible because of the large number of species to be transported. The Hybrid Transported-Tabulated Chemistry method (HTTC) has been designed to overcome these obstacles and radically reduce the computational cost, by transporting only a reduced set of major species and tabulating the intermediate species while making use of their self-similarity property to downsize the table. HTTC has already been validated for light hydrocarbons such as methane. In this work, HTTC is extended to kerosene-air combustion showing that the number of species to be transported is unchanged compared to methane/air and that the self-similarity can still be applied. The chemistry of nitrogen oxides is also addressed with HTTC. The method allows for a reduction of the computational cost by around four orders of magnitude when computing laminar premixed flames. HTTC appears as a flexible tool since its prediction capabilities are maintained even if the table for intermediate species is generated in different conditions than those encountered in the simulation.

    更新日期:2018-06-19
  • Minimum ignition energy for the CH4/CO2/O2 system at low initial temperature
    Fuel (IF 4.601) Pub Date : 2018-06-18
    Gan Cui, Shun Wang, Zhenxiao Bi, Zili Li

    In this paper, the minimum ignition energy (MIE) for methane in an atmosphere of CO2/O2 is measured at 0.1–0.7 MPa and 183–273 K using a gas explosion experimental device that is able to withstand a temperature as low as 113 K. Effects of initial temperature (T0) and initial pressure (P0) on MIE are studied via experiment and a simple theoretical analysis. Results indicate that in our experimental setup, the sensitive conditions of MIE are an equivalence ratio of 1 and an electrode gap of 1 mm. Under low initial temperature, the trends in MIE with respect to initial pressure and temperature in an atmosphere of CO2/O2 are similar to those in an atmosphere of N2/O2. With an increase in initial pressure and temperature, MIE gradually decreases. MIE has a linear correlation with the reciprocal of the square of the initial pressure and the reciprocal of the initial temperature. At low initial temperature, P0 has a large impact on MIE, whereas at low initial pressure, MIE is more sensitive to initial temperature. At the same initial temperature and pressure, MIE in an atmosphere of CO2/O2 is about 1.2 times larger than that in an atmosphere of N2/O2 atmosphere. CO2 is more dilute than N2 in accordance with large heat capacities and small thermal conductivities.

    更新日期:2018-06-19
  • The macroscopic and microscopic analysis on the performance of steam foams during thermal recovery in heavy oil reservoirs
    Fuel (IF 4.601) Pub Date : 2018-06-18
    Zhanxi Pang, Xiaocong Lyu, Fengyi Zhang, Tingting Wu, Zhennan Gao, Zhigang Geng, Chengdong Luo

    In heavy oil reservoirs, steam channeling and steam override seriously decrease oil production and the ultimate oil recovery during steam flooding. Aiming at the two problems, some experiments were carried out to analyze the EOR mechanisms through injecting foaming agents along with steam injection in heavy oil reservoirs. An orthogonal method was employed to analyze the multiple factors on foam’s properties to optimize foaming agent for steam injection. Then a novel 2D-visualization experiment was carried out to quantitatively study the characteristics of steam channeling and the variation of sweep efficiency during steam or steam foams flooding. Based on the experimental results, many bubble’s characteristics, such as migration, retention, regeneration and etc., were analyzed through the macroscopic and microscopic perspectives. The experimental results show that the Jamin effect increases the flow resistance of steam-phase in porous media to obviously enlarge the macro sweep efficiency and effectively increase micro oil displacement efficiency. On a macroscopic level, because of the unique structure, foams decrease steam override or steam channeling to improve sweep efficiency; on a microscopic level, due to the expansion effect of gas-phase, bubbles can desquamate the oil film on the pore wall and even the oil drop in the blind pore to decrease the residual oil saturation. In our experiments, the ultimate recovery of steam flooding can only reach 48.48%. However, the ultimate recovery of steam foams can reach 59.95%, which is 11.47% higher than steam flooding.

    更新日期:2018-06-19
  • In situ experimental and modeling study on coal char combustion for coarse particle with effect of gasification in air (O2/N2) and O2/CO2 atmospheres
    Fuel (IF 4.601) Pub Date : 2018-06-18
    Zhongjie Shen, Liqi Zhang, Qinfeng Liang, Jianliang Xu, Kuangfei Lin, Haifeng Liu

    This study applied the high temperature stage microscope to investigate coal char combustion in air (O2/N2) and O2/CO2 (volume, 21%/79%) atmospheres with the effect of gasification. A reaction front combustion model was also proposed, coupled with effect of char gasification, to predict the key parameters of char combustion in the O2/CO2 atmospheres. The combustion process and particle evolution of coarse chars were observed and measured to calculate the carbon conversion. Experimental results showed that the burnout time of the char particle in the O2/CO2 atmosphere in the was prolonged about 20–25%, compared to the burnout time of chars in air. The overall reaction rates of char particles in the O2/CO2 atmosphere were lower than the rates in the air for different particle sizes. In addition, reaction rates from model prediction showed good agreements with the experimental data for different particle sizes both in the air and O2/CO2 atmospheres, which proved the reaction front combustion model was applicable for the char combustion in this study. The reaction front combustion model also predicted that the reaction front decreased with burning time and mass consumption of char particle. For the char combustion in the O2/CO2 atmosphere, the gasification with CO2 absorbed part of the combustion heat or radiation heat and caused lower particle temperatures and heat fluxes for different particle sizes. The proposed combustion model also predicted that although the effect of the gasification reaction was dominant at the beginning of combustion and then reduced, the conversion of particles was hindered compared to the combustion of char in air.

    更新日期:2018-06-19
  • Low temperature selective catalytic reduction of NOX with NH3 by activated coke loaded with FexCoyCezOm: The enhanced activity, mechanism and kinetics
    Fuel (IF 4.601) Pub Date : 2018-06-18
    Pei Lu, Rui Li, Yi Xing, Yuran Li, Tingyu Zhu, Huifang Yue, Wanrong Wu
    更新日期:2018-06-19
  • Hydrocracking of vacuum residue using nano-dispersed tungsten carbide catalyst
    Fuel (IF 4.601) Pub Date : 2018-06-18
    Chan Hun Kim, Young Gul Hur, Seong Ho Lee, Kwan-Young Lee
    更新日期:2018-06-19
  • A study of the effects of thermal shocks on liberation characteristics of high coal ash particles
    Fuel (IF 4.601) Pub Date : 2018-06-18
    Soni Jaiswal, Rashmi Singh, Veerendra Singh, A.K. Mukherjee

    The influence of thermal shocks on the liberation characteristics of a by-product/discard from a coking coal preparation plant, known as coal middlings were investigated. The coal middlings are characterized by very high ash content (>45%), low carbon content (<35%) along with presence of highly locked mineral particles. Currently they are used in power plant despite having coking coal fractions. So, to extract the coking coal fractions, improved liberation of these particles is required at optimum size. For this purpose, two kinds of thermal shocks viz. microwave pre-treatment and cryogenic grinding were studied. The microwave pre-treatment was used in both dry and wet modes. The exposure time for dry mode was varied from 30 s to 90 s while for wet mode the exposure time was quite high varying from 3 min to 6 min. Results showed slight decrease in ash content of the treated sample than the untreated one. Microscopic analysis confirmed the presence of cracks and fractures in the microwave treated samples with more pronounced observations for wet heating. Among the macerals present in the sample vitrinite was much more effected than inertinite. In terms of recovery the best result was obtained for 6 min wet heating with a combustible matter recovery of 23.3% with product ash of 22% and d80 of around 2 mm. In case of cryogenic grinding, liquid nitrogen was used and soaking time was varied from 20 min to 60 min. Microscopic analysis revealed the presence of cracks and fragmentations in both vitrinite and inertinite particles. However, minor reduction in size was observed with d80 reaching up to a minimum of 6.5 mm with 60 min exposure time. In addition to this marginal increase in BET surface area and pore size of the sample was achieved because of the both pre-treatments. Study reveals that microwave heating is more effective technique than the cryogenic cooling for sizing and liberation of ash particles of coal.

    更新日期:2018-06-19
  • Time-resolved chemical composition of small-scale batch combustion emissions from various wood species
    Fuel (IF 4.601) Pub Date : 2018-06-18
    Miika Kortelainen, Jorma Jokiniemi, Petri Tiitta, Jarkko Tissari, Heikki Lamberg, Jani Leskinen, Julija Grigonyte-Lopez Rodriguez, Hanna Koponen, Sanna Antikainen, Ilpo Nuutinen, Ralf Zimmermann, Olli Sippula

    Small-scale batch combustion of wood is a major source of fine particles, black carbon emission and polycyclic aromatic hydrocarbons in Finland. The mass and chemical compositions of batch combustion emissions are known to be highly time-dependent. In this study, the gaseous and particulate batch combustion emissions of three European wood species (beech, birch and spruce) were quantified in detail with an extensive set of online analysers, including a soot particle aerosol mass spectrometer (SP-AMS) for real-time detection of particulate chemical composition. Ignition and a new batch addition on top of glowing embers were identified as the primary low temperature events during which both particulate and gaseous organic emissions peaked. The flaming combustion created high temperature conditions and produced increased emissions of refractory black carbon (rBC) and PAHs. The residual char combustion phase was characterized by low particulate mass emission consisting mainly of alkali salts and elevated concentrations of gaseous organic emissions and CO. Overall, hardwood species (beech and birch) had the highest PM1 emissions, and the difference between the lowest average emission (spruce) and the highest (birch) was more than 3-fold. The increasing combustion chamber temperature during sequential combustion of wood batches was found to decrease the carbonaceous fraction of the PM as well as OC/EC ratio, as the result of more efficient secondary combustion.

    更新日期:2018-06-19
  • Influence of preheating and thermal power on cyclonic burner characteristics under mild combustion
    Fuel (IF 4.601) Pub Date : 2018-06-18
    Giancarlo Sorrentino, Pino Sabia, Mara de Joannon, Pio Bozza, Raffaele Ragucci

    Autoignition and stabilization of distributed combustion regimes have been proved to occur when a sufficient entrainment of hot species in the fresh reactants jets is reached, thus providing simultaneously for the sensible enthalpy to promote the auto-ignition process and the mass to dilute the incoming fresh reactants. The present study investigates the stabilization process along with the performance of the combustion process in a cyclonic burner operated under MILD combustion conditions. The cyclonic flow has been achieved by means of two pairs of oxidant/fuel jets injected using an anti-symmetric configuration in a prismatic combustion chamber thus realizing a centripetal cyclonic flow field directed toward the top-central gas outlet. Propane/air combustion experimental campaigns without external dilution, on a detailed grid of equivalence ratio and preheating temperature values, at different average residence time and nominal thermal power values were made. In each test condition, temperature measurements inside the chamber and gas sampling analyses have been carried out in order to evaluate the operability range of the cyclonic burner and its performances. These tests allowed to demonstrate the feasibility of stable MILD Combustion regimes in a wide range of operating conditions even when feeding the cyclonic burner with undiluted air. The residence time of the streams inside the burner plays an important role for both reactive structure stabilization and combustion performances/emissions. Significantly, fuel-lean conditions correspond, in the considered cases, to simultaneously low CO and NOx emissions. Furthermore, it has been demonstrated that stable combustion can be sustained in absence of any preheating in a considerable thermal load range and that it is possible, in this condition, to achieve a complete fuel conversion, with a remarkably low pollutant emission for thermal loads up to 8 kW.

    更新日期:2018-06-19
  • Storage period prediction and metal compatibility of endothermic hydrocarbon fuels
    Fuel (IF 4.601) Pub Date : 2018-06-15
    Lin Zhao, Xiangwen Zhang, Lun Pan, Jie Liu
    更新日期:2018-06-16
  • Typical crystal face effects of different morphology ceria on the activity of Pd/CeO2 catalysts for lean methane combustion
    Fuel (IF 4.601) Pub Date : 2018-06-15
    Yanyan Lei, Wenzhi Li, Qingchuan Liu, Qizhao Lin, Xusheng Zheng, Qifu Huang, Shengnan Guan, Xinhua Wang, Chengxin Wang, Fengyu Li

    The catalytic efficiency of CeO2 carriers and the catalytic properties of palladium (Pd) nanocrystals loaded on different morphology CeO2 carrier were studied for lean methane (CH4) combustion. The catalytic activity of simple CeO2 carriers was ranked in the order of rod-CeO2(r-CeO2) > cube-CeO2(c-CeO2) > octahedral-CeO2(o-CeO2). After the Pd species was loaded on CeO2, 90% of CH4 was converted at 348 °C catalyzed by Pd/octahedral-CeO2 (Pd/o-CeO2) with (1 1 1) crystal faces, which had much higher catalytic activity comparing with Pd loaded on c-CeO2 with (1 0 0) crystal faces and r-CeO2 with (1 1 0) and (1 0 0) crystal faces. The results of XRD, HRTEM, EDS, H2-TPR, XPS and elemental mapping showed that the Pd species in the form of Pd0 and PdO were highly dispersed on surface of all CeO2 carriers. Most importantly, quasi In-situ XPS results convinced that Ce3+/Ce4+ ion pairs played an important role in the catalytic combustion of low-concentration methane by adsorbing or releasing oxygen. Compared with r-CeO2 and c-CeO2, the concentration of Ce3+ on the surface of o-CeO2 carrier was greatly increased when the Pd species were present, which indirectly reflected that the concentration of oxygen vacancies on the carrier surface also increased. Consequently, the high catalytic activity of Pd/o-CeO2 is not only related to the high dispersion of Pd0 and PdO species on the surface of the catalyst, but also closely related to the synergistic interaction between Pd species and (1 1 1) specific faces of o-CeO2 exposing.

    更新日期:2018-06-16
  • Phenomenological characterization and investigation of the mechanism of flame spread over butanol-diesel blended fuel
    Fuel (IF 4.601) Pub Date : 2018-06-15
    Manhou Li, Kazui Fukumoto, Changjian Wang, Xiyu Zhang, Shenlin Yang, Xuanya Liu

    The butanol-diesel blended fuel possesses broad application prospects in energy industry owing to its excellent properties; thus, studying on flame spread over the blended fuel is of great significance for both scientific meanings and practical guidelines. Several fundamental parameters of flame spread, including the flame spread rate, frequency of flame oscillation, temperature distribution, and velocity of subsurface flow are characterized. Prior to analyzing the experimental data, a blended fuel flashpoint-prediction model is developed based upon Le Chatelier’s rule, Antoine’s principle, and the ideal liquid evaporation theory. For low ratio of butanol, the calculated values of the butanol-diesel blended fuel flashpoints agree well with those achieved through experimental methodology. The flame spread characteristics of the blended fuel approach those of diesel fuel as the ratio of butanol is less than 17.5%, whereas they resemble those of pure butanol fuel with the ratio of butanol beyond 17.5%. Further, an increase in the ratio of butanol leads to an increase in the flame spread rate as well as the velocity of subsurface flow. The findings of the present work are useful to provide the basic data for butanol-diesel blended fuel spilling fire, and also to develop some fire prevention measures.

    更新日期:2018-06-16
  • Transformation mechanism of sodium during pyrolysis of Zhundong coal
    Fuel (IF 4.601) Pub Date : 2018-06-15
    Lianfei Xu, Hui Liu, Deng Zhao, Qingxi Cao, Jihui Gao, Shaohua Wu
    更新日期:2018-06-16
  • Multi-component gas mixture transport through porous structure of coal
    Fuel (IF 4.601) Pub Date : 2018-06-15
    Karolina Wojtacha-Rychter, Adam Smoliński

    A study of gas flow through porous coals is significantly important for the accurate assessment of the state of endogenous fire risk. Coal characterizes of a unique pore structure which provides a good storage capacity and an ideal transport pathway for the movement of gases. Gaseous products released from the source of coal self-heating flow through coal and may be subject to adsorption. In this study, the effects of the transport of multi-component gas mixture through a sorption column filled with granular coal and inert material were investigated. The experiment with coal presented in the paper proved that gas concentrations at the inlet (Co) and at the outlet of the sorption column (Ck) varied depending on the properties of coal and gas molecules. Based on the results, an index demonstrating the relationship between these concentrations was calculated. The experiment of gas mixture flow through inert material confirmed that the lowest index, i.e. below 0.7, obtained for propylene and acetylene in the experiment with coal was a result of sorption processes. Gases with lowest critical temperatures, such as carbon monoxide and hydrogen had the highest index which was above 0.9.

    更新日期:2018-06-16
  • Hydrocarbon saturation in Bakken Petroleum System based on joint inversion of resistivity and dielectric dispersion logs
    Fuel (IF 4.601) Pub Date : 2018-06-15
    Pratiksha Tathed, Yifu Han, Siddharth Misra

    Bakken Petroleum System (BPS) is composed of both conventional and unconventional units, which exhibits significant variations in lithology, rock texture, clay content, total organic carbon, accompanied by high connate water salinity, presence of disseminated pyrite grains, and low values of porosity. These petrophysical attributes of the BPS lead to inconsistency in the oil-in-place estimates for those obtained from Electromagnetic (EM) induction log, Nuclear Magnetic Resonance (NMR) log, dielectric dispersion log measured by Array Dielectric Tool (ADT), and Dean-Stark core measurements. For purposes of improved hydrocarbon saturation estimation and petrophysical characterization in the BPS, a joint-inversion-based interpretation was performed on dispersive electrical conductivity and dielectric permittivity measurements at 4 dielectric-log-acquisition frequencies and 1 induction resistivity acquired at 20 kHz. This analysis was performed across a 350-ft depth interval in one of the science wells intersecting the BPS. Three geo-electromagnetic mixing models, namely Complex Refractive Index model, Stroud-Milton-De model, and Waxman Smits model are integrated and coupled to the inversion scheme to simultaneously estimate water saturation, formation brine conductivity, cementation exponent and saturation exponent in BPS. Water saturation estimates obtained using the proposed interpretation method were compared against those obtained from NMR log, Dean-Stark core measurements and service company’s dielectric inversion. In Middle Bakken from depth XX720 to XX750 ft, our estimates of water saturation are in better agreement with those estimated by service company’s mineral inversion method and service company’s dielectric interpretation as compared to those obtained from NMR interpretation and Dean Stark core measurement. Water saturation and formation brine conductivity estimates in Middle Bakken are in the ranges of 0.5–1 and 25–45 S/m, respectively. Inversion-derived brine conductivity and saturation exponent estimates are most uncertain in Lodgepole and Three Forks 2 formations, which exhibit a wide range of pore size distribution. Average relative errors in matching the 1 induction resistivity and 8 dielectric dispersion logs using the inversion-derived estimates are 33% and 20%, respectively, in the 350-ft depth interval of BPS. The proposed inversion achieves high certainty for the estimates when the formation has low clay content, low electrical anisotropy, and high porosity.

    更新日期:2018-06-16
  • Autoignition and flame spectroscopy of propane mixture in a rapid compression machine
    Fuel (IF 4.601) Pub Date : 2018-06-15
    T. Goyal, D. Trivedi, O. Samimi Abianeh

    The autoignition process of propane has been studied using an optically accessible rapid compression machine (RCM). The ignition delay times of the fuel were measured at two compressed pressures of approximately 21 and 30 bar, equivalence ratios of 0.5, 0.8, 1.0 and 1.2, and at various compressed gas temperatures. A detailed kinetic model was also used to simulate the autoignition. A new methodology was also developed and discussed to include the effect of heat transfer in the mechanism model simulation. The combustion process imaging was acquired using high-speed camera and the deflagration like combustion with blue continuum spectrum was observed close to the end of ignition delay at all of the studied conditions, excluding the condition with very long ignition delay (e.g., 90 ms). The deflagration concluded with detonation for most of the studied conditions. The excited radicals’ chemiluminescence emissions were acquired using flame spectrometer and Electron-Multiplying Charge-Coupled Device (EMCCD) with wavelength ranging from 280 nm to 700 nm. Several excited radicals were detected during autoignition process and their time-resolved intensity as a function of mixture conditions (pressure, temperature and equivalence ratio) were studied.

    更新日期:2018-06-16
  • Risk evaluation of coal spontaneous combustion on the basis of auto-ignition temperature
    Fuel (IF 4.601) Pub Date : 2018-06-15
    Yutao Zhang, Yurui Liu, Xueqiang Shi, Chaoping Yang, Weifeng Wang, Yaqing Li

    The spontaneous combustion of coal, if not eradicated immediately, may lead to coal ignition and even a full-blown fire. A new method, DSC Inflection Point (DSCIP), was proposed to determine the coal auto-ignition temperature (CAIT). Heat fluxes and kinetic parameters before and after CAIT were comparatively investigated through TG/DSC analysis and mathematical model construction. Meanwhile, the impacts of temperature rise rate and oxygen concentration on CAIT were studied and two indexes representing the hazard and destructiveness of coal spontaneous combustion, respectively, were proposed. The results demonstrated that the heat flux curve of coal spontaneous combustion can be well fitted using Gaussian mixture model. Compared to the oxidation stage, the released heat during the combustion stage was greatly increased. Furthermore, the activation energy became larger and the reaction order decreased to zero when the temperature exceeded CAIT. The study also found that CAIT was enhanced with the increase of temperature rise rates or the decrease of oxygen concentrations. Changes of heat flux, free radicals, and the activation energy proved the rationality and feasibility of the DSCIP method in determining CAIT. Additionally, under the same environmental conditions, lignite had the largest hazard of coal spontaneous combustion and the anthracite had the biggest destructiveness. Both the hazard and the destructiveness of coal spontaneous combustion became stronger as oxygen concentrations increased.

    更新日期:2018-06-16
  • Effects of CO2 gasification reaction on the combustion of pulverized coal char
    Fuel (IF 4.601) Pub Date : 2018-06-15
    Yanqing Niu, Siqi Liu, Bokang Yan, Shuai Wang, Xiao Zhang, Shi'en Hui

    Although numerous studies on CO2 gasification during coal char combustion have been documented, the effects of CO2 gasification on high-temperature carbon oxidation, which is important for evaluation of carbon conversion during pulverized coal combustion under oxy-fuel and flue gas recirculation conditions, are unclear. Thus, the char conversion characteristics at various contents of O2 and CO2 were studied in a drop-tube furnace at 1373 K. Due to the cumulative effects of CO2 gasification, which can not only suppress carbon conversion due to endothermicity but also consume part of carbon directly, there exists a minimal carbon conversion point around the CO2 content of 9–13 vol%, where the growth of promotion effect with CO2 content catches up with the suppression effect, and an inflection point around the CO2 content of 17–25 vol%, where the promotion effect of the direct gasification reaction on carbon consumption surpasses the suppression effect. Increasing O2 shifts both points towards high CO2 contents, whereas increasing combustion gas temperature decreases the values. A mathematical formula including oxidation, effect of gasification on oxidation, and CO2 gasification, is presented, which gives well prediction on high-temperature carbon conversion. With increasing CO2 content, the reduction degree of CO2 gasification on oxidation rate increases, and the synthesis oxidation rate slightly decreases, whereas there always exists a minimal point for gasification rate, gross carbon conversion rate, and gasification weightiness. With increasing O2 content, the oxidation rate, reduction degree of CO2 gasification on oxidation rate, and gross carbon conversion rate increase; the gasification rate increases below the minimal point, whereas decreases above the minimal point; the gasification weightiness decreases. Combustion gas temperature shows positive effect on all abovementioned parameters. The results derived here provide meaningful guidelines for practical application and kinetics research on pulverized coal combustion.

    更新日期:2018-06-16
  • Semi-empirical model for the engine liquid fuel sheet formed by the oblique jet impinging onto a plate
    Fuel (IF 4.601) Pub Date : 2018-06-15
    Ruixiang Wang, Yong Huang, Xiang Feng, Lei Sun, Di Wang, Zhilin Liu

    Operating conditions and fuel properties are important to the atomization quality, which is an inevitable problem that the liquid fuel has to face, specifically for new alternative fuels. One of the recognized atomization methods is the liquid sheet formed by the oblique fuel jet or spray impinging onto a plate in a direct injection (DI) engine. In this paper, a series of experiments that deal with the sheet, are carried out under different operating conditions. Meanwhile, a semi-empirical model fitted for new alternative fuels is established to predict the shape and the size of the sheet. The predictions of the model are in good agreement with the experimental data. Based on the experiments and predictions, the specific effect of the dynamic viscosity, the surface tension, the impingement velocity and the impingement angle on the sheet were analyzed, respectively. It is found that the sheet consists of a thin liquid layer and a thick rim which connects the outer and the inner border lines. With the decrease of the dynamic viscosity, the size of both the outer and inner border lines of the sheet will non-linearly increase. The gradient of the size of the border lines is decreased with the increase of the dynamic viscosity. With the decrease of the surface tension coefficient, the size of the border lines will gradually increase. The size of the border lines will linearly increase with the increasing impingement velocity. With the increase of the impingement angle, the border lines will gradually become circles. The semi-empirical model that is established with reasonable assumptions, can help fuel developers to assess the potential atomization quality of their new fuels.

    更新日期:2018-06-16
  • Methane hydrate formation in mixed-size porous media with gas circulation: Effects of sediment properties on gas consumption, hydrate saturation and rate constant
    Fuel (IF 4.601) Pub Date : 2018-06-15
    Baoyong Zhang, Junjie Zheng, Zhenyuan Yin, Changling Liu, Qiang Wu, Qiong Wu, Chuanhai Liu, Xia Gao, Qiang Zhang
    更新日期:2018-06-16
  • Effect of alkaline earth metal oxide (MO) Cu/MO/Al2O3 catalysts on methanol synthesis activity and selectivity via CO2 reduction
    Fuel (IF 4.601) Pub Date : 2018-06-15
    Venkata D.B.C. Dasireddy, Neja Strah Štefančič, Matej Huš, Blaž Likozar
    更新日期:2018-06-16
  • Conversion of bio-derived phenolic compounds into aromatic hydrocarbons by co-feeding methanol over γ-Al2O3
    Fuel (IF 4.601) Pub Date : 2018-06-15
    Zhan Si, Wei Lv, Zhipeng Tian, Kang Bi, Xinghua Zhang, Chenguang Wang, Changle Pang, Renjie Dong, Longlong Ma
    更新日期:2018-06-16
  • Chemical speciation and leaching characteristics of hazardous trace elements in coal and fly ash from coal-fired power plants
    Fuel (IF 4.601) Pub Date : 2018-06-14
    Shilin Zhao, Yufeng Duan, Jincheng Lu, Rajender Gupta, Deepak Pudasainee, Shuai Liu, Meng Liu, Jianhong Lu

    This work reports the chemical speciation and leaching characteristics of seven hazardous trace elements (HTEs, including Hg, As, Cr, Cd, Ba, Mn, and Pb) in the coal and fly ash samples collected from four coal-fired power plants in China. The physical structure and chemical composition of the fly ash were characterized by the scanning electron microscope (SEM) and the energy dispersive X-ray spectrometer (EDX). The chemical speciation of HTEs in the coal and fly ash was measured by the modified three-step sequential extraction method, proposed by the European Community Bureau of Reference (BCR). Leaching characteristics of HTEs in the fly ash were investigated by a single batch leaching test. The concentration of HTEs in solid and liquid samples was determined by the direct mercury analyzer DMA 80 (Hg in solid) and the inductively coupled plasma-mass spectrometry (ICP-MS). Results show that for the coal, concentration of Hg, As, Cr, Cd, Ba, Mn, and Pb is 0.06–0.22, 0.63–4.01, 8.91–13.09, 0.06–0.15, 108.67–229.21, 49.94–100.24 and 6.74–26.38 mg/kg, respectively. Mercury is mainly in the residual form while Cd and Ba are primarily in reducible form. Compared with other HTEs, manganese in water/acid soluble and exchangeable fraction has the large percentage. For the fly ash, the concentration of Hg, As, Cr, Cd, Ba, Mn and Pb is 0.17–1.26, 5.15–25.74, 43.25–64.61, 0.56–0.70, 777.05–970.70, 163.83–831.47 and 28.94–119.57 mg/kg, respectively. Mercury and chromium are mainly in the residual speciation. Arsenic and manganese in water/acid soluble and exchangeable form have high ratio with value of 7.27–58.60% and 6.14–62.27%, respectively. Cadmium and barium are primarily in the reducible form. Based on the risk assessment code, manganese in the coal can pose high or very high risk on the environment. Leaching concentration of Cr in some fly ash is higher than permissible limits and the pH value of leaching solution for the fly ash is alkaline. Considering huge fly ash production from coal combustion and complex landfill conditions, some suitable disposal measures to minimize the risk on the environment are needed.

    更新日期:2018-06-15
  • Experimental data and prediction of normal boiling points of partial acylglycerols
    Fuel (IF 4.601) Pub Date : 2018-06-14
    Daniela S. Damaceno, Evandro P. Jesus, Roberta Ceriani
    更新日期:2018-06-15
  • Late Jurassic bituminous shales from Marib oilfields in the Sabatayn Basin (NW Yemen): Geochemical and petrological analyses reveal oil-shale resource
    Fuel (IF 4.601) Pub Date : 2018-06-08
    Mohammed Hail Hakimi, Adel M. Al-Matary, Osman Salad Hersi

    In this study, bituminous shale samples were collected from Late Jurassic sedimentary section in the Marib oilfields to study their petrologic and organic geochemical properties. The results of this study indicate that the Late Jurassic bituminous shales can be considered as an oil-source rocks in the Sabatayn Basin (NW Yemen). The analyzed Late Jurassic shales have high organic matter (TOC up to 10%) content of kerogen Types I/II. These kerogen types in the analyzed samples are consistent with the high dominance of alginite and amorphous organic matter. Open pyrolysis–gas chromatography results are generally consistent with the Rock-Eval results and further indicate that the analyzed shale samples contain Types I/II and II-S kerogen and generally can produce paraffinic oils with low to high wax content. Type II-S kerogen can produce oil with high sulphur content at low maturity level. The maturity data reflect immature and very early maturity stages of petroleum formation of the Late Jurassic bituminous shales. Therefore, the kerogen types in the Late Jurassic bituminous shales has not been altered by thermal maturity for oil generation, thus, artificial heating is required of kerogen cracking generate significant oil.

    更新日期:2018-06-10
  • Influence of the temperature in the yield and composition of the bio-oil from the pyrolysis of spent coffee grounds: Characterization by comprehensive two dimensional gas chromatography
    Fuel (IF 4.601) Pub Date : 2018-06-09
    Carmem T. Primaz, Tiago Schena, Eliane Lazzari, Elina B. Caramão, Rosângela A. Jacques

    Coffee is an important agricultural product being one of the most consumed beverages in the world. The goal of this work is to apply the pyrolysis to this residue for the production of bio-oil. The pyrolysis of the biomass (SCG) was done in a fixed bed reactor and varying the final temperature (400, 450, 500, 550 and 600 °C). The higher crude bio-oil yield was obtained at 500 °C with a flow of N2 in 100 mL/min (mass yield = 30.51%). The bio-oil produced by pyrolysis of SCG had its chemical composition analyzed by comprehensive two-dimensional gas chromatography coupled to mass spectrometry detector (GC × GC/TOF-MS) and associated with LTPRI. This bio-oil showed potential for the production of chemical and liquid fuels, evidencing to be a good option for the destination of this waste. Its composition showed high amount of phenols, fatty acids and nitrogen compounds. The major compounds in the bio-oil sample were n-hexadecanoic acid (palmitic acid) (19%), 9-octadecenoic acid (oleic acid) (11%), octadecanoic acid (stearic acid) (10%).

    更新日期:2018-06-10
  • Virgin coconut oil (VCO) and potassium glycinate (PG) mixture as absorbent for carbon dioxide capture
    Fuel (IF 4.601) Pub Date : 2018-06-07
    Hanan Mohamed Mohsin, Khairiraihanna Johari, Azmi Mohd Shariff
    更新日期:2018-06-09
  • Development of oxide-supported nickel-based catalysts for catalytic decomposition of dimethyl sulfide
    Fuel (IF 4.601) Pub Date : 2018-06-08
    Naohiro Shimoda, Nao Koide, Masaki Kasahara, Takashi Mukoyama, Shigeo Satokawa
    更新日期:2018-06-09
  • Lithotype-based modelling and simulations of coal degradation conditioned by both high and low energy breakage
    Fuel (IF 4.601) Pub Date : 2018-06-06
    Fengnian Shi, Hongping Liu, Sandra Rodrigues, Joan Esterle, Anh K. Nguyen, Emmanuel Manlapig

    The control of coal fragmentation and fines generation during mining and processing is important in coal production. A method to characterise, model and simulate coal size degradation and fines generation based on lithotypes has been developed. This method was refined to cover both high energy single impact to mimic blasting and crushing and low energy incremental breakage to mimic coal handling, transiting, stockpiling and processing. The JKRBT was utilised to characterise high energy single impact breakage and drop shatter tests were used to characterise low energy incremental breakage. X-ray Computed Tomography (XCT) scanning was used as an undisruptive technique to estimate size distributions of drill cores in the drop shatter tests. The JK size-dependent breakage model was applied for breakage characterisation, size degradation modelling and fines generation simulation. The results indicate that coal lithotype has a significant influence on coal degradation and fines generation. This paper has demonstrated that the adaption of two distinct breakage characterisation tests and linkage via the one model is a significant advance in quantifying coal degradation and fines generation during coal production.

    更新日期:2018-06-08
  • Chemical characteristics of filterable and condensable PM2.5 emissions from industrial boilers with five different fuels
    Fuel (IF 4.601) Pub Date : 2018-06-07
    Hsi-Hsien Yang, S. Md. Arafath, Kuei-Ting Lee, Yueh-Shu Hsieh, Yi-Te Han

    This study investigated the chemical characteristics of fine particulate matter (PM2.5) emitted from industrial boilers, each utilizing one of five fuels, including solid (coal, wood), liquid (heavy oil, diesel) and gas (natural gas) phase. The investigated boilers are abbreviated as CFBs, WFBs, HOFBs, DFBs and NGFBs respectively. A field sampling campaign was conducted to collect both filterable particulate matter (FPM) and condensable particulate matter (CPM) samples using USEPA Method 201A and Method 202 respectively. Mass concentrations and chemical compositions (including carbon contents, water-soluble ions and metal elements) of the collected PM2.5 samples were analyzed. PM2.5 (FPM + CPM) emission concentrations for CFBs, WFBs, HOFBs, DFBs and NGFBs were found to be 46.6 ± 6.43, 122 ± 54.7, 191 ± 68.5, 7.94 and 7.37 ± 3.29 mg/Nm3 respectively. Results suggest that OC was dominant in the flue gas of solid fuel (CFBs and WFBs) combustion, and high EC emitted from liquid fuel (HOFBs and DFBs) combustion for FPM. Inorganic fraction accounted for more than 50% of total CPM for solid- (CFBs and WFBs) and gas-fuel (NGFBs) boilers, whereas organic fraction was mainly composed in total CPM for liquid-fuel (HOFBs and DFBs) boilers. The contents of water-soluble ions (SO42−, NO3−, NH4+ and Cl−) were significantly enriched in PM2.5. Na, Ca and K were predominant in CPM for all types of boilers.

    更新日期:2018-06-08
  • A systematic numerical modeling study of various polymer injection conditions on immiscible and miscible viscous fingering and oil recovery in a five-spot setup
    Fuel (IF 4.601) Pub Date : 2018-06-07
    Abhijit Chaudhuri, R. Vishnudas

    Polymer flooding is employed to prevent immiscible viscous fingering between oil and water. If the polymer injection concentration is decreased rapidly, there is a high chance that fast growing miscible viscous fingers will pierce through the polymer bank and enter the oil bank. This is very detrimental to oil production. We performed numerical modeling of polymer flooding in one-quarter of a five-spot system. Due to the nonuniform flow field in a five-spot setup, the fingering patterns are very different and miscible fingers are more detrimental in this case than in a rectangular domain. In this paper we quantify the impact of injection concentration and duration of polymer flooding on the growth rate of miscible and immiscible viscous fingers. Besides decrease and increase of immiscible and miscible viscous finger growth at the front and rear of polymer banks respectively, we have shown that the residual oil saturation decreases for higher injection concentrations. However for high injection concentrations, polymer should be injected for a long duration so that the width of the polymer bank is large and miscible fingers cannot cause short-circuiting. Since injection at constant concentration for a long duration is not optimal, simulations for different multi-step injection were performed. Our results demonstrate that arbitrary decreases in polymer injection concentration are not effective for enhancing oil recovery. The ideal polymer injection scheme suggested by our simulations should involve an initial constant rate, followed by a gradual decrease. This is mainly to overcome the retardation due to adsorption of the polymer.

    更新日期:2018-06-08
  • Autoignition studies of Liquefied Natural Gas (LNG) in a shock tube and a rapid compression machine
    Fuel (IF 4.601) Pub Date : 2018-06-07
    Sonal K. Vallabhuni, Aditya D. Lele, Vaibhav Patel, Arnas Lucassen, Kai Moshammer, Mohammed AlAbbad, Aamir Farooq, Ravi X. Fernandes

    Liquefied Natural Gas (LNG) has become an increasingly important world energy resource and is a part of the European Union clean fuel strategy launched in 2013. Therefore, there are currently several ongoing measurement strategies considering quality specification of LNG. In this context, for application in gas engines, it is essential to understand the combustion behavior of these natural gas mixtures. The methane number (MN) which represents a scale for the knocking propensity, is one of the main indicators for this combustion behavior. In this study, we investigated the influence of the LNG composition on the ignition delay time and thus the knocking behavior of prototypical LNG Mixtures. Several LNG typical mixtures containing CH4/C2H6/C3H8/n-C4H10/i-C4H10/n-C5H12/i-C5H12/N2 were studied in the temperature range 850–1450 K, with pressures of 20 and 40 bar and at equivalence ratios of 0.4 and 1.2. The use of a shock tube and a rapid compression machine facility allowed us to study the ignition behavior over a wide range of operating conditions relevant to gas engines. We report a detailed investigation of LNG autoignition with respect to temperature, pressure and equivalence ratio thereby providing crucial validation data for chemical kinetic models for real applications.

    更新日期:2018-06-08
  • A novel method to estimate subsurface shale gas capacities
    Fuel (IF 4.601) Pub Date : 2018-06-05
    Hexin Huang, Wei Sun, Fengyang Xiong, Lei Chen, Xin Li, Tian Gao, Zhenxue Jiang, Wei Ji, Yanjun Wu, Jin Han
    更新日期:2018-06-07
  • Influence of coal moisture on initial gas desorption and gas-release energy characteristics
    Fuel (IF 4.601) Pub Date : 2018-06-05
    Chaojie Wang, Shengqiang Yang, Jinhu Li, Xiaowei Li, Chenglin Jiang

    Coal and gas outbursts (hereinafter referred to as ‘outbursts’) result in serious damage and often occur in tectonically-deformed coal that is rich in gas. It has been demonstrated that the level of outburst risk declines with increasing coal moisture content. Moreover, an outburst generally lasts for mere tens of seconds and the required energy is mainly provided by the gas expansion energy. However, the gas desorption and energy release characteristics of tectonically deformed coal with different moisture contents during the first dozen seconds have not often been studied. In this study, a set of self-designed gas desorption equipment was used to carry out gas adsorption-desorption experiments in the first dozen seconds (about 13 s) on coal with different moisture contents. The results show that the drop rate of the gas pressure increases with an increase in coal moisture content, and the total amount of gas desorption and the mass flow rate of gas desorption reduce correspondingly in the gas desorption process. Moreover, the gas velocity also slows with increasing moisture content. Under different gas pressures, the total gas expansion energy (TGEE) and the total gas energy (TGE) released from the coal decrease with the increasing moisture content. Correspondingly, it takes a shorter time for coal to release 90% of the TGEE and the TGE. For all of the coal samples, the time taken for releasing 90% of the TGEE is shorter than that for releasing 90% of the TGE. Meanwhile, the ratio of TGEE in the TGE increases with the increasing moisture content. The TGEE accounts for 14–16% of the TGE released from coal samples of different moisture contents under different gas pressures.

    更新日期:2018-06-07
  • Modeling investigation of low salinity water injection in sandstones and carbonates: Effect of Na+ and SO42−
    Fuel (IF 4.601) Pub Date : 2018-06-06
    Cleverson Esene, David Onalo, Sohrab Zendehboudi, Lesley James, Amer Aborig, Stephen Butt

    Low salinity water injection (LSWI) has gained great attention as a promising enhanced oil recovery (EOR) method with numerous advantages (e.g., economic and environmental aspects), compared to other conventional chemical EOR methods. For the past two decades, a number of laboratory studies have been performed by researchers to understand the main pore-scale mechanisms of oil displacement during LSWI; however, further experimental and modeling research works are required to comprehend the LSWI governing mechanisms. The focus of this paper is to investigate important aspects such as oil recovery mechanisms, wettability alteration, changes in pH of formation water, and mineral reactions (dissolution/precipitation) which occur during LSWI in sandstones and carbonates. To explore the effect of ion-exchange, a compositional model is developed with the aid of laboratory data provided by Computer Modeling Group (CMG), where Na+ and SO42− are used as interpolants to model LSWI in sandstone and carbonate cores, respectively. In this study, it is concluded that wettability change from preferentially oil-wet to more water-wet is the dominant mechanism for a considerable increase in the oil recovery in carbonate rocks. Based on the simulation runs, the amount of calcite precipitation and dissolution is found to be small in the carbonate case studied in this research work; exhibiting an insignificant impact. However, the calcite precipitation and dolomite dissolution are the central factors, affecting oil recovery during LSWI if there is a high bicarbonate content <img height="17" border="0" style="vertical-align:bottom" width="56" alt="View the MathML source" title="View the MathML source" src="https://origin-ars.els-cdn.com/content/image/1-s2.0-S0016236118310068-si1.gif">(HCO3-), in the presence of other catalytic ions.

    更新日期:2018-06-07
  • Structural transformation of fluid phase extracted from coal matrix during thermoplastic stage of coal pyrolysis
    Fuel (IF 4.601) Pub Date : 2018-06-06
    Shuxing Qiu, Shengfu Zhang, Yue Wu, Guibao Qiu, Chenggong Sun, Qingyun Zhang, Jie Dang, Liangying Wen, Meilong Hu, Jian Xu, Rongjin Zhu, Chenguang Bai
    更新日期:2018-06-07
  • Content of potassium and other aerosol forming elements in commercially available wood pellet batches
    Fuel (IF 4.601) Pub Date : 2018-06-06
    A. Pollex, T. Zeng, J. Khalsa, U. Erler, R. Schmersahl, C. Schön, D. Kuptz, V. Lenz, M. Nelles

    In wood fuels, potassium is by far the most abundant aerosol forming component. Given this predominant role, a major contribution for meeting the tightened total particulate matter emission thresholds on European level could thus be expected by the introduction of an upper limit for potassium content in wood pellets. To evaluate options to introduce such an upper limit for the potassium content of wood pellets, an extensive pellet screening was performed in Germany covering 22 of the 46 ENplus certified wood pellet producers representing more than 50% of the current German wood pellet production of about 2 million t/year. This screening was accompanied by the compilation of wood pellet fuel data from different sources. In total, analysis data of 249 high quality wood pellet samples has been evaluated. Almost all pellet samples originated from European production whereof the majority were pellets from certified German pellet producers. The pellet screening revealed a very large variation in the potassium content of high quality wood pellets ranging from below detection limit to well above 1000 mg/kg d.b. The results also confirmed the predominant role of potassium among the aerosol forming elements potassium, sodium, lead and zinc in wood samples. Furthermore, the screening highlighted that the ash content is not sufficient to evaluate the potassium content of wood pellets. Analysis of selected raw materials from three different pellet producers revealed a strikingly large variation in the potassium content of the raw materials. Consequently, controlled adjustment of the potassium content in wood pellets in the production process would require dedicated mixtures of different raw materials and the limitation of the share of raw materials with particularly high potassium contents. In this way, the potassium content of wood pellets could be limited and this could contribute to the compliance with strict particulate emission thresholds for small scale combustion appliances. Prerequisite for such an approach would be a fast, simple and cheap possibility to determine the potassium content of raw materials for wood pellet production at the production sites and the incorporation of the potassium control in the quality assurance of the pellet production process. Consequently, wood pellets could be produced that facilitate compliance with particulate matter emission threshold without secondary emission reduction measures.

    更新日期:2018-06-07
  • Removal of nitrogen from chicken manure anaerobic digestion for enhanced biomethanization
    Fuel (IF 4.601) Pub Date : 2018-06-06
    Kun Li, Ronghou Liu, Qiong Yu, Ruijie Ma

    The effects of side-stream ammonia stripping as a pre- and post-treatment on the anaerobic mono-digestion of chicken manure were investigated in laboratory-scale continuous stirred tank reactors. Ammonia stripping columns were operated at pH 10 but different temperatures (35, 55, 70 °C). Results showed that digestate stripping at 70 °C and pH 10 got the highest ammonia removing rate (18.2–45.2%), and under these conditions, the methane yield at OLR of 9 g VS L−1 d−1 reached 0.199 L g−1 VSadded which was significantly higher than that of other digesters (0.01–0.03 L g−1 VSadded), although no improvement of methane yield was observed at OLR 3 and 6 g VS L−1 d−1. The microbial community analysis revealed that hydrolytic and fermentative bacteria dominated all bacterial communities. Methanogenic pathway of feedstock stripping digester was predominant by hydrogenotrophic Methanimicrococcus, while hydrogenotrophic/aceticlastic Methanoscarcina was dominant in the archaeal structures of the rest digesters. However, a shift from Methanosarcina to Methanoculleus was observed in R3 (digestate stripping at 70 °C/pH 10) when dominant species were inhibited and decreased in other digesters, indicating that the high methanogenic activity in R3 was maintained by shifting to methanogens with high tolerance to inhibitors.

    更新日期:2018-06-07
  • Structure and morphology variation of solid residue from co-liquefaction of lignite and Merey atmospheric residue
    Fuel (IF 4.601) Pub Date : 2018-06-05
    Tengfei Yang, Yong Qin, Huanshuang Meng, Wenan Deng, Chuan Li, Juntao Du, Qingshan Niu

    Structural features of the co-liquefaction solid residue (CLSR) from the co-liquefaction of lignite and Merey atmospheric residue (MRAR) were analyzed to investigate the internal correlation relevant to the hydroconversion process of the reaction system. The feedstocks were loaded by using different catalysts, which resulted in a series of CLSRs with different hydroconversion degree after co-liquefaction. The experimental results showed that the carbonaceous solid conversion efficiency was related to the H/C atomic ratio and O content of the CLSR. X-ray diffraction (XRD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis were used to study the structural parameter changes of the CLSRs from co-liquefaction with different catalysts. Experimental data of the selected analytical parameters exhibited credible relationship with the carbonaceous solid conversion efficiency. Considering the structure variation of CLSRs was clearly associated with the conversion of co-liquefaction, the utilization of linear fitting for the approximate evaluation of carbonaceous solid conversion efficiency was suggested. A comparison of the particle-size distribution and microscopic morphology of different CLSRs showed that the small mean particle diameter and a fragmented CLSR shape resulted as distinctive features for the high hydroconversion of co-liquefaction. Besides, the microscopic feature variation indicated the inhibition of coke formation in the reaction system was crucial to improve the hydroconversion degree of co-liquefaction of lignite and heavy oil.

    更新日期:2018-06-06
  • Solvent effect of gamma-valerolactone (GVL) on cellulose and biomass hydrolysis in hot-compressed GVL/water mixtures
    Fuel (IF 4.601) Pub Date : 2018-06-04
    Bing Song, Yun Yu, Hongwei Wu

    This study employs a semi-continuous reactor system to investigate the solvent effect of gamma-valerolactone (GVL) on cellulose hydrolysis in hot-compressed GVL/water (HCGW) at 250 °C and 10 MPa. The primary liquid products from cellulose hydrolysis in HCGW at various GVL concentrations are collected and characterised. Both hydrolysis reaction rate and final glucose recovery are found to increase with GVL concentration, with a high glucose recovery of 91% achieved in the primary liquid products of cellulose hydrolysis in 10% GVL/water. Further analyses of the primary liquid products using high performance anion exchange chromatography with pulsed amperometric detection show the reductions in the isomers of glucose oligomers (with reducing end as fructose and mannose) and the increases in the glucose oligomers with low degrees of polymerisation, indicating that GVL addition enhances hydrolysis reactions but suppresses isomerization reactions in the solid phase. Similar effects are also found in the secondary reactions of the primary liquid products during cellulose hydrolysis at reduced flow rates. The experimental results from biomass hydrolysis clearly demonstrate that GVL/water co-solvent is an excellent reaction medium for biomass hydrolysis under acid-free conditions, achieving a near-complete sugar recovery (i.e., 93%) at a low GVL concentration of 5%.

    更新日期:2018-06-06
  • Investigation of moisture effect on methane adsorption capacity of shale samples
    Fuel (IF 4.601) Pub Date : 2018-06-05
    Jie Zou, Reza Rezaee, Quan Xie, Lijun You, Kouqi Liu, Ali Saeedi

    The existing moisture in shale samples makes the evaluation for shale gas reservoirs more difficult due to its impact on the methane adsorption capacity and pore structure measurements. This paper compares the pore structure characteristics and methane adsorption capacity between dry and wet shale samples from Perth Basin, Western Australia. Pores with size between 0.4 nm and 100 nm were quantified by low-pressure N2 and CO2 adsorption. The comparative results demonstrate that moisture could alter the pore size distribution for big pores (>16 nm) and small pores (0.4–16 nm) in different ways.For each sample, the moisture effect on methane adsorption in shales changes with pressure: moisture effect on methane adsorption is more pronounced at lower pressure than higher pressure. For all samples, the effect of moisture on methane adsorption is related to the total organic carbon (TOC) content. Moisture could reduce methane adsorption by blocking clay- hosted small pores directly and organic matter-hosted small pores indirectly in high TOC samples. This phenomenon can effectively lead to a reduced Langmuir volume (VL) and increased Langmuir pressure (PL) when moisture exists.

    更新日期:2018-06-06
  • Experimental and kinetic modeling investigation on methyl decanoate pyrolysis at low and atmospheric pressures
    Fuel (IF 4.601) Pub Date : 2018-06-05
    Yitong Zhai, Chengcheng Ao, Beibei Feng, Qinghui Meng, Yan Zhang, Bowen Mei, Jiuzhong Yang, Fuyi Liu, Lidong Zhang

    The pyrolysis of methyl decanoate (MD), an ideal surrogate of biodiesels, was investigated in a flow reactor at the pressures of 30 and 760 Torr and the temperature ranging from 773 to 1198 K. A great variety of pyrolysis products including free radicals, n-alkanes, 1-alkenes, alkynes, unsaturated esters and aromatics were comprehensively observed and identified by employing synchrotron vacuum ultraviolet photoionization mass spectrometry. A new kinetic model for MD pyrolysis was constructed and applied to validate the experimental data. Modeling analyses involving rate of production analysis and sensitivity analysis were performed to help explore the pyrolysis kinetics of MD and the formation mechanisms of key species. The analysis results show that the decomposition of MD is determined by the H-abstraction and unimolecular dissociation reactions during the whole pyrolysis process, whereas the contributions of H-abstraction reactions are enhanced as the pressure elevates. C4-C9 unsaturated esters are principally yielded from the β-scission of ester radicals; while the β-scission reactions of MD radicals are responsible for the formation of C5-C9 1-alkenes. In addition, 1-alkenes can be further decomposed to form small radicals and molecules. Through the combination reactions such as the reaction routes of C3 + C3, C4 + C2 and C5 + C2, these radicals and molecules can be transformed into benzene and benzyl radical, which are demonstrated as the crucial precursors of polycyclic aromatic hydrocarbons. In conclusion, the pyrolysis of MD would not only significantly enhance the cognitions of various pollutant formation mechanisms but also have a guiding significance for the combustion in the fuel-cooled engine.

    更新日期:2018-06-06
  • Effect of particle size on particulate matter emissions during biosolid char combustion under air and oxyfuel conditions
    Fuel (IF 4.601) Pub Date : 2018-06-02
    Sui Boon Liaw, Xujun Chen, Yun Yu, Mário Costa, Hongwei Wu

    In an industrial scale furnace, solid fuels can be fired in a wide range of particle sizes. This study aims to investigate the effect of the particle size on particulate matter (PM) emissions during combustion under air and oxyfuel (30% O2/70% CO2) conditions. Biosolid chars prepared from the pyrolysis of three different biosolid particle sizes at 1300 °C were burned in a drop tube furnace. The experimental results indicate that a shift from small to large char particles leads to >55% reduction in PM1–10 emission when combustion occurs in air, likely due to less intense char fragmentation experienced by the large char particles. Such a reduction originates from a decrease in Mg, Ca, P, Si, Al and some trace elements (V, Co, Cu, Zn and Mn) release as PM1–10. In contrast, PM1 emission is not affected by the char particle size. However, under oxyfuel conditions, the PM1–10 emission from the small char particles is ∼65% of that released during combustion in air. In addition, the PM1–10 emission from large char particles only reduced by ∼27% when compared to that from small char particles. This observation is likely to result from the coalescence of ash particles to form PM with particle sizes >10 µm due to the increase surface mobility caused by repeated formation and decomposition of CaCO3 in the ash.

    更新日期:2018-06-04
  • Understanding desorption of oil fractions from mineral surfaces
    Fuel (IF 4.601) Pub Date : 2018-06-02
    Xingang Li, Yun Bai, Hong Sui, Lin He

    Separation of heavy hydrocarbons from mineral surfaces is highly dependent on the oil composition and their host rock surface properties. Herein, the petroleum is divided into SARA fractions (saturates, aromatics, resins, asphaltenes) to investigate their desorption behaviors on different types of mineral surfaces (silica (SiO2), kaolinite (Al2Si2O5(OH)4) and calcium carbonate (CaCO3)). The Quartz Crystal Microbalance with Dissipation (QCM-D) tests show that the saturates and aromatics could desorb from the mineral surfaces spontaneously even in water, while no desorption was observed for the asphaltenes and resins. Although the above desorption could be enhanced by alkaline or surfactant solutions, great difference still appears to different oil fractions. Oil characterization shows that the heavy fractions (i.e., asphaltenes, resins) possess richer acid groups than those of light fractions, allowing the stronger affinity of heavy fractions to the mineral surfaces through polar and chemical interactions. Additionally, the heavy fractions dominate in determining the desorption properties of bitumen (the mixed fractions), and lead to more significant wettability alteration to the mineral surfaces. Furthermore, the oil fractions desorption is also found to be highly influenced by the mineral types. Compared with silica, kaolinite has stronger affinity to the heavy oil fractions, leading to smaller amount of desorption. While on the calcium carbonate surface, less than 11% of the coated oil fractions are observed to be desorbed. Surface characterizations summarize that, due to the difference in mineral composition, the affinity of minerals to oil components in aqueous solutions is given as: calcium carbonate (positively charged calcium ions) > kaolinite (containing –AlOH, –SiOH groups and heavy metal elements) > silica (–SiOH group). The above results reveal the differences among bitumen subfractions and mineral types, allowing potential insights to the development of enhanced oil recovery, such as aqueous-nonaqueous hybrid extraction process, solvent extraction, CO2-enhanced oil recovery, etc.

    更新日期:2018-06-04
  • An integrated experimental approach to quantify the oil recovery potential of seawater and low-salinity seawater injection in North Sea chalk oil reservoirs
    Fuel (IF 4.601) Pub Date : 2018-06-02
    Mojtaba Seyyedi, Stefano Tagliaferri, Jimmie Abatzis, Sidsel Marie Nielsen

    In this study, the oil recovery potential of seawater (SW), SW with different ion compositions, low-salinity seawater (LSSW), and formation water (FW), is investigated, using chalk reservoir cores and crude oil from the North Sea. Furthermore, the impact of temperature on SW flooding performance is addressed.A series of flooding experiments were conducted at reservoir conditions (2800 psi and 60 °C), followed by spontaneous imbibition tests. Secondary SW and FW flooding led to the same oil recovery. Tertiary SW injections, performed after secondary FW flooding and secondary LSSW injection, did not lead to any extra oil recovery at 60 °C. Injecting SW at 100 °C did not lead to additional recovery either. Spiking the SO4−2 content of SW by four times, at 60 °C, did not show any additional oil production as well as increasing the concentration of Ca+2 and the Ca+2/Mg+2 ratio at 60 °C. Conversely, tertiary LSSW injection, after secondary SW injection, led to 2.5% OOIP additional oil recovery. More importantly, secondary LSSW injection, compared to the secondary SW and FW injection, led to around 8% OOIP extra oil recovery. Consistently, the results of the imbibition test showed the same trend: tertiary LSSW imbibition, after secondary SW imbibition, led to 4.25% OOIP extra oil recovery.This study, through employing chalk reservoir cores and crude oil, reveals that LSSW flooding in examples of silica containing chalk reservoirs in the North Sea, has a better oil recovery potential compared to both SW and FW flooding. This is in contrast to other published results as it will be discussed in the paper.

    更新日期:2018-06-04
  • Effects of the variation in diesel fuel components on the particulate matter and unregulated gaseous emissions from a common rail diesel engine
    Fuel (IF 4.601) Pub Date : 2018-06-02
    Zilong Li, Guibin Liu, Xianfeng Cui, Xingyu Sun, Shuai Li, Yong Qian, Chenxu Jiang, Xingcai Lu
    更新日期:2018-06-04
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
化学 • 材料 期刊列表