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1.	Ahmed, Trifa Mohammad, et al. (författare) Emissions of particulate associated oxygenated and native polycyclic aromatic hydrocarbons from vehicles powered by ethanol/gasoline fuel blends 2018 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 214, s. 381-385 Tidskriftsartikel (refereegranskat)abstract Emission factors for oxygenated polycyclic aromatic hydrocarbons (OPAHs) and PAHs have been determined from two different fuel flexible light duty vehicles operated at -7 degrees C in the New European Driving Cycle (NEDC) and at +22 degrees C in the Artemis Driving Cycle (ADC). Three different gasoline/ethanol blends, commercially available in Sweden, were tested i.e., gasoline E5, with 5% v/v ethanol and ethanol fuel E85 with 85% v/v ethanol and winter time quality E70 with 70% v/v ethanol, respectively. The results showed greatly increased emissions of both OPAHs and PAHs at cold engine start conditions (-7 degrees C in the NEDC) compared to warm engine start (+ 22 degrees C in the ADC). For the OPAHs, higher average total emission factors were obtained when running on E85 compared to E5 at both cold 2.72 mu g/km vs 1.11 mu g/km and warm 0.19 mu g/km vs 0.11 mu g/km starting conditions with the highest emissions when using E70 at -7 degrees C 4.12 mu g/km. The same trend was found for the PAHs at cold engine start with higher average total emission factors when using ethanol fuel 71.5 mu g/km and 60.0 mu g/km for E70 and E85, respectively compared to gasoline E5 (20.2 mu g/km). Slightly higher average total PAH emissions were obtained when operating at + 22 degrees C with E5 compared to with E85 1.23 mu g/km vs 0.72 mu g/km.
2.	Andersson, Jim, et al. (författare) Co-gasification of pyrolysis oil and black liquor for methanol production 2015 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 158, s. 451-459 Tidskriftsartikel (refereegranskat)abstract One alternative to reduce the motor fuel production cost and improve the operational flexibility of a black liquor gasification (BLG) plant is to add pyrolysis oil to the black liquor feed and co-gasify the blend. The objective of this study was to investigate techno-economically the possibility to increase methanol production at a pulp mill via co-gasification of pyrolysis oil and black liquor. Gasifying a blend consisting of 50% pyrolysis oil and 50% black liquor on a wet mass basis increases the methanol production by more than 250%, compared to gasifying the available black liquor only. Co-gasification would add extra revenues per produced unit of methanol (IRR > 15%) compared to methanol from unblended BLG (IRR 13%) and be an attractive investment opportunity when the price for pyrolysis oil is less than 70 €/MW h. The economic evaluation was based on a first plant estimate with no investment credit for the recovery boiler and a methanol product value volumetric equivalent to conventional ethanol, both these conditions will not applicable when the technology has been fully commercialized.
3.	Azuara, Manuel, et al. (författare) Influence of pressure and temperature on key physicochemical properties of corn stover-derived biochar 2016 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 186, s. 525-533 Tidskriftsartikel (refereegranskat)abstract This study focuses on analyzing the effect of both the peak temperature and pressure on the properties of biochar produced through slow pyrolysis of corn stover, which is a common agricultural waste that currently has little or no value. The pyrolysis experiments were carried out in a fixed-bed reactor at different peak temperatures (400, 525 and 650 degrees C) and absolute pressures (0.1, 0.85 and 1.6 MPa). The inert mass flow rate (at NTP conditions) was adjusted in each test to keep the gas residence time constant within the reactor. The as-received corn stover was pyrolyzed into a biochar without any physical pre-treatment as a way to reduce the operating costs. The properties of biochars showed that high peak temperature led to high fixed-carbon contents, high aromaticity and low molar H:C and O:C ratios; whereas a high pressure only resulted in a further decrease in the O:C ratio and a further increase in the fixed-carbon content. Increasing the operating pressure also resulted in a higher production of pyrolysis gas at the expense of water formation.
4.	Bach Oller, Albert, et al. (författare) Co-gasification of black liquor and pyrolysis oil at high temperature : Part 2. Fuel conversion 2017 Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 197, s. 240-247 Tidskriftsartikel (refereegranskat)abstract The efficiency and flexibility of the BL gasification process may improve by mixing BL with more energy-rich fuels such as pyrolysis oil (PO). To improve understanding of the fuel conversion process, blends of BL and PO were studied in an atmospheric drop tube furnace. Experiments were performed in varying atmosphere (5% and 0% CO2, balanced by N2), temperature (800–1400 °C), particle size (90–200 μm and 500–630 μm) and blending ratio (0%, 20% and 40% of PO in BL on weight basis). Additionally, pine wood was used as a reference fuel containing little alkali. The addition of PO to BL significantly increased the combined yield of CO and H2 and that of CH4. BL/based fuels showed much lower concentration of tar in syngas than pine wood. Remarkably, the addition of PO in BL further promoted tar reforming in presence of CO2. Unconverted carbon in the gasification residue decreased with increasing fractions of PO. Small fuel particles showed complete conversion at 1000 °C but larger particles did not reach complete conversion even at T = 1400 °C.
5.	Bach Oller, Albert, et al. (författare) Co-gasification of black liquor and pyrolysis oil at high temperature : Part 1. Fate of alkali elements 2017 Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 202, s. 46-55 Tidskriftsartikel (refereegranskat)abstract The catalytic activity of alkali compounds in black liquor (BL) enables gasification at low temperatures with high carbon conversion and low tar and soot formation. The efficiency and flexibility of the BL gasification process may be improved by mixing BL with fuels with higher energy content such as pyrolysis oil (PO). The fate of alkali elements in blends of BL and PO was investigated, paying special attention to the amount of alkali remaining in the particles after experiments at high temperatures. Experiments were conducted in a drop tube furnace under different environments (5% and 0% vol. CO2 balanced with N2), varying temperature (800–1400 °C), particle size (90–200 µm, 500–630 µm) and blending ratio (0%, 20% and 40% of pyrolysis oil in black liquor). Thermodynamic analysis of the experimental cases was also performed.The thermodynamic results qualitatively agreed with experimental measurements but in absolute values equilibrium under predicted alkali release. Alkali release to the gas phase was more severe under inert conditions than in the presence of CO2, but also in 5% CO2 most of the alkali was found in the gas phase at T = 1200 °C and above. However, the concentration of alkali in the gasification residue remained above 30% wt. and was insensitive to temperature variations and the amount of PO in the blend. Thermodynamic analysis and experimental mass balances indicated that elemental alkali strongly interacted with the reactor’s walls (Al2O3) by forming alkali aluminates. The experience indicated that adding PO into BL does not lead to alkali depletion during high temperature gasification.
6.	Baina, Fabiola, et al. (författare) Extended operability of a commercial air-staged burner using a synthetic mixture of biomass derived gas for application in an externally fired micro gas turbine 2015 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 150, s. 664-671 Tidskriftsartikel (refereegranskat)abstract Biomass gasification converts solid biomass into a gaseous fuel that is more versatile and can be used in many applications. However, biomass gasification gas contains some contaminants and inert compounds. The contaminants can cause several problems in the downstream equipment and undesirable emissions while the inert compounds can affect the lower heating value of the gas. Because of these characteristics, there have been difficulties in finding a conversion technology using biomass gasification gas for heat and power generation. In this regard, externally fired gas turbines open a possibility for this combustible gas since due to its configuration, combustion takes place outside the conventional gas turbine cycle. For this reason, combustion studies of biomass derived gas are important. In this work the operability of a commercial air-staged natural gas burner is shown in terms of CO, UHC, and NOX emissions using a synthetic mixture of biomass gasification gas. Two fuel gas mixtures simulating the composition of biomass gasification gas are injected in the combustor. Each fuel gas contains different injection rates of benzene in order to represent tars and to understand their effect on the combustion performance. Additionally, the equivalence ratio is varied in a range of lean conditions in order to find an optimum operation point for the burner studied. The results showed that the presence of polyaromatic hydrocarbons such as benzene reduced the CO concentrations in the exhaust gas while it increased the concentrations of unburned hydrocarbons (UHC) at equivalence ratios lower than 0.68. Additionally, NOX emissions showed a relatively constant trend over the range of equivalence ratios studied for both fuels. It was also observed that NOX emissions increase with the addition of benzene in the fuel gas. An optimum point with regards CO and UHC concentrations was found for the fuels tested.
7.	Chelgani, Saeed Chehreh, et al. (författare) Explaining relationships between coke quality index and coal properties by Random Forest method 2016 Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 182, s. 754-760 Tidskriftsartikel (refereegranskat)abstract In this study was shown that random forest (RF) can be used as a sensible new data mining tool for variable importance measurements (VIMs) through various coal properties for prediction of coke quality (Free Swelling Index (FSI)). The VIMs of RF within coal analyses (proximate, ultimate, and petrographic analyses) were applied for the selection of the best predictors of FSI over a wide range of Kentucky coal samples. VIMs assisted by Pearson correlation through proximate, ultimate, and petrographic analyses indicated that volatile matter, carbon, vitrinite, and Rmax (coal rank parameters) are the most effective variables for the prediction of FSI. These important predictors have been used as inputs of RF model for the FSI prediction. Outputs in the testing stage of the model indicated that RF can predict FSI quite satisfactorily; the R2 was 0.93 and mean square error from actual FSIs was 0.15 (had less than interval unit of FSI; 0.5). According to the result, by providing nonlinear inter-dependence approximation among parameters for variable selection and also non-parametric predictive model RF can potentially be further employed as a reliable and accurate technique for the determination of complex relationship through fuel and energy investigations.
8.	Chelgani, Saeed Chehreh, et al. (författare) Relationships between noble metals as potential coal combustion products and conventional coal properties 2018 Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 226, s. 345-349 Tidskriftsartikel (refereegranskat)abstract Increasing coal consumption has generated million tons of ash and caused various environmental issues. Exploring statistical relationships between concentrations of valuable metals in coal and other coal properties may have several benefits for their commercial extraction as byproducts. This investigation studied relationships between conventional coal concentrations and concentration of noble metals for a wide range (708 samples) of eastern Kentucky coal samples (EKCS) by statistical methods. The results indicate that there are significant positive Pearson correlations (r) > 0.90 among all noble metals (Au, Pt, Pd, Ru and Rh) except for Ag (r < 0.2). The results also showed that the noble metals (except Ag) are associated with the minerals of the coal and have high positive correlations with ash (and high negative correlations with the organic fraction). Modeling through the database demonstrated that the highest Au concentrations in the EKCS occur when Si is between 6000 and 8000 ppm and Fe is below 10000 ppm, and the highest Ag was observed when both Cu and Ni were over 40 ppm. Outcomes suggested that aluminosilicate minerals and pyrite are possibly the main host of noble metals (except Ag) in the EKCS whereas Ag might occur in various forms including organic association, mineral species, and as a native metal.
9.	Christensen, Moah, et al. (författare) The temperature dependence of the laminar burning velocities of methyl formate plus air flames 2015 Ingår i: Fuel. - : Elsevier BV. - 1873-7153 .- 0016-2361. ; 157, s. 162-170 Tidskriftsartikel (refereegranskat)abstract Laminar burning velocities, S-L, of methyl formate and air flames were determined at atmospheric pressure and initial gas temperatures, T, of 298, 318, 338 and 348 K. Measurements were performed in non-stretched flames, stabilized on a perforated plate burner at adiabatic conditions, generated using the heat flux method. These new experimental data shed light on discrepancies seen in previously published results, and the temperature dependence of the laminar burning velocity of methyl formate was analysed using expression S-L = S-L0(T/T-0)(alpha). It was found that the power exponent, alpha, has a minimum close to equivalence ratio, phi, of 1.0. Both the laminar burning velocities and alpha coefficient were compared with predictions of the mechanisms of Glaude et al. (2005), Dooley et al. (2010) and Dievart et al. (2013). While the two latter mechanisms are in generally good agreement in lean mixtures, the Glaude mechanism over predicts the experimental burning velocities over the entire range of equivalence ratios. The temperature dependences predicted by the Glaude and Dievart mechanisms, however, are rather close and agree well with the measurements. To elucidate these differences and similarities in the performance of two mechanisms, the sensitivity analysis of the power exponent alpha was performed for the first time. It was demonstrated that examination of the temperature dependence of the burning velocity provides an independent approach for analysis of experimental data consistency. (c) 2015 Elsevier Ltd. All rights reserved.
10.	Cifuentes, Luis, et al. (författare) Chemical Explosive Mode Analysis for a Jet-in-Hot-Coflow burner operating in MILD combustion 2018 Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 232, s. 712-723 Tidskriftsartikel (refereegranskat)abstract Large Eddy Simulations (LES) of Moderate and Intense Low oxygen Dilution (MILD) combustion of a Jet-in-HotCoflow (JHC) burner were performed using detailed chemistry. On the contrary to traditional flames, where heat release is occurring in very thin fronts, MILD combustion occurs in the distributed reaction regime where the reaction zone is broad, thus, this paper applies a direct Arrhenius closure with detailed chemistry to resolve important details of the fuel oxidation reactions. Comparisons of LES results are in good agreement with experiments, demonstrating that the simulations capture the intermediate species and finite reaction rate effects. A Chemical Explosive Mode Analysis (CEMA) was used to determine the flame structure and to detect the pre-and post-ignition regions, including the contributions to the CEMs analyzing the Explosion Index (EI) and Participation Index (PI). To the best of our knowledge, a detailed study of CEMA on MILD or flameless regime has never been reported. The flame structure was clearly visualized with CEMA, as well as the lean and the rich flame fronts. Different flame zones close to the anchoring points of these turbulent lifted flames were selected and the analysis demonstrates the contributions of dominant chemical species, such as HO2 and O. The reactions related to the dominant local CEM were obtained to highlight the nature of the stabilization in these highly diluted operating conditions.
11.	Edo, Mar, et al. (författare) The combined effect of plastics and food waste accelerates the thermal decomposition of refuse-derived fuels and fuel blends 2016 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 180, s. 424-432 Tidskriftsartikel (refereegranskat)abstract Mechanical treatments such as shredding or extrusion are applied to municipal solid wastes (MSW) to produce refuse-derived fuels (RDF). In this way, a waste fraction (mainly composed by food waste) is removed and the quality of the fuel is improved. In this research, simultaneous thermal analysis (STA) was used to investigate how different mechanical treatments applied to MSW influence the composition and combustion behaviour of fuel blends produced by combining MSW or RDF with wood in different ratios. Shredding and screening resulted in a more efficient mechanical treatment than extrusion to reduce the chlorine content in a fuel, which would improve its quality. This study revealed that when plastics and food waste are combined in the fuel matrix, the thermal decomposition of the fuels are accelerated. The combination of MSW or RDF and woody materials in a fuel blend has a positive impact on its decomposition.
12.	Gallo, Yann, et al. (författare) Investigation of Late-Cycle Soot Oxidation Using Laser Extinction and In-Cylinder Gas Sampling at Varying Inlet Oxygen Concentrations in Diesel Engines 2017 Ingår i: Fuel. - : Elsevier BV. - 1873-7153 .- 0016-2361. ; 193, s. 308-314 Tidskriftsartikel (refereegranskat)abstract This study focuses on the relative importance of O2 and OH as oxidizers of soot during the late cycle in diesel engines, where the soot oxidation is characterized in an optically accessible engine using laser extinction measurements. These are combined with in cylinder gas sampling data from a single cylinder engine fitted with a fast gas sampling valve. Both measurements confirm that the in-cylinder soot oxidation slows down when the inlet concentration of O2 is reduced. A 38% decrease in intake O2 concentration reduces the soot oxidation rate by 83%, a non-linearity suggesting that O2 in itself is not the main soot oxidizing species. Chemical kinetics simulations of OH concentrations in the oxidation zone and estimates of the OH soot oxidation rates point towards OH being the dominant oxidizer.
13.	Gao, Qiuju, et al. (författare) Evaluation of solvent for pressurized liquid extraction of PCDD, PCDF, PCN, PCBz, PCPh and PAH in torrefied woody biomass 2015 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 154, s. 52-58 Tidskriftsartikel (refereegranskat)abstract Biomass torrefaction for sustainable energy production has gained an increasing interest. However, there is a lack of information on the thermal formation of persistent organic pollutants such as dioxins in the torrefied solid product. In this paper, we investigated the applicability of pressurized liquid extraction (PLE) for simultaneous extraction of a number of polychlorinated planar aromatic compounds from torrefied wood. The targeted compounds included polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), naphthalenes (PCNs), benzenes (PCBz), phenols (PCPhs) and PAHs. PLE tests were conducted on torrefied and non-torrefied (i.e. raw) eucalyptus wood chips using 5 single solvents (n-hexane, toluene, dichloromethane, acetone and methanol) and a mixture of n-hexane/toluene (1:1, v/v). The performance of each solvent was evaluated in terms of recoveries of spiked internal standards and the amount of co-extracted sample matrix. High polarity solvents such as methanol and acetone resulted in poor recoveries from torrefied wood for most of the target compounds, probably due to the high co-extraction of thermally degraded lignocellulosic compounds. Raw wood was less solvent-dependent and comparable results were obtained for polar and non-polar solvents. Toluene showed the best performance of the investigated solvents, with average recoveries of 79 +/- 14% and 66 +/- 9% for raw and torrefied wood, respectively. The method was validated using pentachlorophenol-tainted spruce wood chips. The proposed PLE method was compared to the traditional Soxhlet method. Results show that PLE gave equivalent or better extraction for all target compounds.
14.	Goswami, M., et al. (författare) Experimental and modelling study of the effect of elevated pressure on ethane and propane flames 2016 Ingår i: Fuel. - : Elsevier BV. - 1873-7153 .- 0016-2361. ; 166, s. 410-418 Tidskriftsartikel (refereegranskat)abstract Laminar burning velocities, S-L, of ethane + air and propane + air flames within an equivalence ratio range between 0.8 and 1.3 were determined at atmospheric and elevated pressures up to 4 atm. Measurements were performed in non-stretched flames, stabilized on a perforated plate burner at adiabatic conditions, created using the heat flux method. Initial unburnt gas temperature was 298 K. These new experimental results were compared with available literature data and predictions using three kinetic schemes: USC Mech II, San Diego mechanism and Aramco Mech 1.3. The models behave differently in reproducing S-L of ethane and propane flames with closer agreement between Aramco Mech 1.3 and the present measurements. The pressure dependence of the laminar burning velocities was analysed using the expression S-L = S-L0(P/P-0)(beta). Large deviations of the derived power exponent, beta, were observed for different experimental datasets and between model predictions and the measurements. To elucidate these differences in the performance of the three mechanisms, sensitivity analyses of the burning velocity and of the power exponent beta were performed. It was demonstrated that the power exponent beta may serve as an independent target for model validation and improvement. When comparing beta coefficients derived from the present and previous measurements of S-L in methane, ethane, propane and n-pentane flames using the heat flux method, important similarities were found at lean conditions with large disparity in rich mixtures. Neither experiments nor modelling support the linear dependence of the power exponent beta with equivalence ratio for flames of alkanes. (C) 2015 Elsevier Ltd. All rights reserved.
15.	Guo, K., et al. (författare) In-situ heavy and extra-heavy oil recovery : A review 2016 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 185, s. 886-902 Tidskriftsartikel (refereegranskat)abstract Due to the growing global energy demand and increasingly limited availability of conventional or easy-to-produce crude oils, extensive attention is being paid to the exploitation of unconventional heavy and extra-heavy oils. However, their inherent properties, characterized by high viscosity and poor mobility, coupled with the complex reservoir configuration, make the desired recovery processes very challenging. Although several in-situ recovery techniques have been employed in oil reservoirs worldwide, most of them are still suffering from low sweep and displacement efficiencies, high capital investment, potential formation damage and negative environmental footprints. This paper aims to provide a comprehensive review of the existing in-situ heavy oil recovery techniques, which fall into three categories of thermal injection, chemical injection and gas injection. Different aspects including the fundamental principles, main features, applicability, and limitations of these recovery processes are elaborated sequentially to illustrate the current technology status. Underlying mechanisms causing the relatively low recovery factors will also be pinpointed. Furthermore, this paper focuses on the technology using novel and active catalysts for simultaneous heavy oil upgrading and recovery, especially in the case of metallic nanocatalysts. Rationales, advantages and challenges regarding this in-situ catalytic upgrading technology will be extensively described for their potential implementation in fields. It is noteworthy that many recovery techniques are still limited to the laboratory scale with needs for further investigations. Therefore, this paper also covers the evaluation standards and analytical methodologies of heavy and extra-heavy oil recovery to establish experimental screening criteria. In the end, economic and environmental aspects of the in-situ catalytic upgrading technology have been briefly discussed. The objective of this review is to present a wide range of expertise related to the in-situ heavy oil recovery processes, and to introduce the in-situ catalytic upgrading technology as an effective and environmental friendly heavy oil recovery process.
16.	Guo, Kun, et al. (författare) Monodispersed nickel and cobalt nanoparticles in desulfurization of thiophene for in-situ upgrading of heavy crude oil 2018 Ingår i: Fuel. - : ELSEVIER SCI LTD. - 0016-2361 .- 1873-7153. ; 211, s. 697-703 Tidskriftsartikel (refereegranskat)abstract Monodispersed nickel (Ni) and cobalt (Co) nanoparticles (NPs) with different sizes are synthesized via the thermal decomposition of organometallic precursors by controlling the reaction temperature and surfactant amount. X-ray diffraction analysis of the as-prepared NP samples shows the formation of cubic Ni metal phases with good crystallinity, while the cubic Co metal samples are semi-amorphous. Transmission electron microscopy characterization further confirms that two Ni NP samples with average sizes of 9 and 27 nm, and Co NPs with an average size of 6 nm are successfully prepared with a narrow size distribution. Furthermore, catalytic performance of these monodispersed NPs towards the hydrodesulfurization (HDS) reaction, which plays a pivotal role in the upgrading of heavy crude oil, is evaluated under reservoir-relevant conditions using thiophene as a sulfur-containing model compound. Different parameters including particle size, catalyst dosage, hydrogen donor ratio, temperature, and reaction duration are systematically studied to optimize the catalytic HDS performance. The morphology and size of the spent NP catalysts after the reaction are also analyzed. The results show that the 9 nm Ni NPs exhibit the best HDS activity and stability compared with other catalysts, which suggests that such well-dispersed Ni NPs are promising candidates for the in-situ upgrading and recovery of heavy crude oil from underground reservoirs.
17.	Göktepe, Burak, et al. (författare) Soot reduction in an entrained flow gasifier of biomass by active dispersion of fuel particles 2017 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; , s. 111-117 Tidskriftsartikel (refereegranskat)abstract Soot is an undesired by-product of entrained flow biomass gasification since it has a detrimental effect on operation of the gasifier, e.g. clogging of flow passages and system components and reduction of efficiency. This study investigated how active flow manipulation by adding synthetic jet (i.e. oscillating flow through orifice) in feeding line affects dispersion of fuel particles and soot formation. Pine sawdust was gasified at the conditions similar to pulverized burner flame, where a flat flame of methane-air sub-stoichiometric mixture supported ignition of fuel particles. A synthetic jet flow was supplied by an actuator assembly and was directed perpendicular to a vertical tube leading to the center of the flat flame burner through which pine sawdust with a size range of 63-112. μm were fed into a reactor. Quartz filter sampling and the laser extinction methods were employed to measure total soot yield and soot volume fraction, respectively. The synthetic jet actuator modulated the dispersion of the pine sawdust and broke up particle aggregates in both hot and cold gas flows through generation of large scale vortex structures in the flow. The soot yield significantly reduced from 1.52. wt.% to 0.3. wt.% when synthetic jet actuator was applied. The results indicated that the current method suppressed inception of young soot particles. The method has high potential because soot can be reduced without changing major operation parameters. © 2016.
18.	H. Moud, Pouya, et al. (författare) Biomass pyrolysis gas conditioning over an iron-based catalyst for mild deoxygenation and hydrogen production 2017 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 211, s. 149-158 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract Bio-crude is a renewable source for production of valuable energy carriers. Prior to its utilization, a conditioning step of the raw pyrolysis gas can be beneficial before the bio-crude is converted via catalytic hydrodeoxygenation (HDO) into liquid hydrocarbon products, or via steam reforming (SR) to synthesis gas/hydrogen. An experimental small industrial scale study for the chemistry of atmospheric pressure pyrolysis gas conditioning resulting in bio-crude deoxygenation and a hydrogen-rich gas using an iron-based catalyst without addition of hydrogen or steam is presented and discussed. Following a short catalyst stabilization period with fluctuating bed temperatures, the catalyst operated near 450°C at a space velocity of 1100 h-1 for 8 hours under stable conditions during which no significant catalyst deactivation was observed. Experimental results indicate a 70-80% reduction of acetic acid, methoxy phenols, and catechol, and a 55-65% reduction in non-aromatic ketones, BTX, and heterocycles. Alkyl phenols and phenols were least affected, showing a 30-35% reduction. Conditioning of the pyrolysis gas resulted in a 56 % and a 18 wt% increase in water and permanent (dry) gas yield, respectively, and a 29 % loss of condensable carbon. A significant reduction of CO amount (-38 %), and production of H2 (+1063 %) and CO2 (+36 %) over the catalyst was achieved, while there was no or minimal change in light hydrocarbon content. Probing the catalyst after the test, the bulk phase of the catalyst was found to be magnetite (Fe3O4) and the catalyst exhibited significant water gas shift (WGS) reaction activity. The measured gas composition during the test was indicative of no or very limited Fischer-Tropsch (FT) CO /CO2 hydrogenation activity and this infers that also the active surface phase of the catalyst during the test was Fe-oxide, rather than Fe-carbide. The results show that iron-based materials are potential candidates for application in a pyrolysis gas pre-conditioning step before further treatment or use, and a way of generating a hydrogen-enriched gas without the need for bio-crude condensation.
19.	Han, Tong, et al. (författare) Characterization of lignin at pre-pyrolysis temperature to investigate its melting problem 2019 Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 235, s. 1061-1069 Tidskriftsartikel (refereegranskat)abstract Technical lignin particles melt under relatively low temperature. This results in the problem in the continuous feeding and fluidization during lignin pyrolysis, which in turn limits its utilization on a large scale. In this study, two most available types of lignin have been used to investigate the lignin melting problem, which are Kraft lignin (KL) from pulping process and hydrolysis lignin (HL) from bio-ethanol production process. Elemental composition, thermal property and thermally decomposed derivatives of each sample are tested by elemental analyzer, TGA, DSC, and Py-GC/MS. Morphology, structure and crystal change before and after heat treatment are tested by microscopy, FTIR and XRD. All results suggest that lignin structure determines its melting properties. Kraft lignin from pulping process contains a less cross-linked structure. It melts under heating. On the other hand, hydrolysis lignin from hydrolysis process contains a highly crossed-linked and condensed structure. It does not melt before decomposition under heat treatment. Modifying lignin structure is suggested for the resolution of technical lignin melting problem.
20.	Holmgren, Per, et al. (författare) Size, shape, and density changes of biomass particles during rapid devolatilization 2017 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 206, s. 342-351 Tidskriftsartikel (refereegranskat)abstract Particle properties such as size, shape and density play significant roles on particle flow and flame propagationin pulverized fuel combustion and gasification. A drop tube furnace allows for experiments athigh heating rates similar to those found in large-scale appliances, and was used in this study to carryout experiments on pulverized biomass devolatilization, i.e. detailing the first stage of fuel conversion.The objective of this study was to develop a particle conversion model based on optical informationon particle size and shape transformation. Pine stem wood and wheat straw were milled and sieved tothree narrow size ranges, rapidly heated in a drop tube setup, and solid residues were characterized usingoptical methods. Different shape descriptors were evaluated and a shape descriptor based on particleperimeter was found to give significant information for accurate estimation of particle volume. The opticalconversion model developed was proven useful and showed good agreement with conversion measuredusing a reference method based on chemical analysis of non-volatilized ash forming elements.The particle conversion model presented can be implemented as a non-intrusive method for in-situ monitoringof particle conversion, provided density data has been calibrated.
21.	Ivo Achu, Nges, et al. (författare) Physio-chemical pretreatments for improved methane potential of Miscanthus lutarioriparius 2016 Ingår i: Fuel. - : Elsevier BV. - 1873-7153 .- 0016-2361. ; 166, s. 29-35 Tidskriftsartikel (refereegranskat)abstract Bio-energy production from lignocelluloses biomass has gained a lot of interest in recent years. Miscanthus sp. are high lignocelluloses biomass yielding with relatively high carbohydrate content cultivable on different soils and under climatic conditions. However, the lignocellulosic nature means that cellulose and hemicellulose are cover by lignin network that might limit hydrolysis. In this study, physical pretreatments (size reduction), physiochemical (steam expulsion) and chemical pre-treatments (mild acid and alkaline) were investigated in a view to improve the anaerobic biodegradability of Miscanthus lutarioriparius for biogas production. Prior to the pretreatment and methane potential test, the compositional analyses of M. lutarioriparius was performed in order unveil the carbohydrate (cellulose and hemicelluloses), protein and lignin contents. From these analyses, the maximum theoretical methane potential was estimated. All pretreatments led to solubilisation of organic matter as was evidenced by increase dissolve COD and ammonium nitrogen. There was a positive correlation between dissolved COD and methane yields meanwhile a negative correlation was observed for reducing sugar and methane yields. The achieved methane yields ranged from 121 to 238 ml CH4/g VS. Steam explosion, 0.3 M NaOH treatment and 0.5 mm size reduction led to the highest increases in methane yields, which was in the order of 57% with regard to the untreated samples. These improvements resulted in 71% of theoretical methane yield of M. lutarioriparius. Alkaline pretreatment in particular also improve the rate of methane production as was evidenced by the fact that as high 15% of the final methane yield that was achieve on the first day as compared to only 3% for the untreated sample. Indeed, the time to reach 90% of the ultimate methane yield was reduced by 13 days following 0.3 M NaOH treatment. M. lutarioriparius may therefore represent an interesting candidate as a lignocellulosic feedstock for biogas production after suitable pretreatment. (C) 2015 Elsevier Ltd. All rights reserved.
22.	Ji, Jie, et al. (författare) Experimental study of non-monotonous sidewall effect on flame characteristics and burning rate of n-heptane pool fires 2015 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 145, s. 228-233 Tidskriftsartikel (refereegranskat)abstract To study the influence of sidewall effect on flame characteristics and burning rate, a series of experiments with heptane pools was conducted. The results showed that as the fires were placed close to the sidewall, the flames inclined to the sidewall due to the restriction on air entrainment, and the burning rate increased on the whole, which could be mainly due to the enhanced radiation from the heated sidewall and ceiling flame. However, regardless of fuel pool shape, the burning rate obtained the peak value when the fire was near the sidewall, rather than attached to the sidewall, resulting from less flame radiation from the vertical flame part to the fuel in the latter case. The ratio of longitudinal ceiling flame length to transverse length tended to decrease with the fire moving close to the sidewall. For cases with the largest length and wall fires, the ratio was nearly 0.5, which could be explained according to the theory of mirror effect. Also, due to the non-monotonous sidewall effect, a higher burning rate did not necessarily lead to a larger ceiling flame length.
23.	Konwar, Lakhya Jyoti, et al. (författare) Reaction kinetics with catalyst deactivation in simultaneous esterification and transesterification of acid oils to biodiesel (FAME) over a mesoporous sulphonated carbon catalyst 2016 Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 166, s. 1-11 Tidskriftsartikel (refereegranskat)abstract In this work, a careful analysis of the reaction kinetics upon simultaneous esterification and transesterification of acidic oils over a mesoporous sulphonated carbon catalyst is discussed. A batch reactor system was used and the synthesized carbon catalyst were characterized by N2-physisorption, transmission electron microscopy, elemental analysis and NH3-TPD. A second order pseudo-homogeneous kinetic model was proposed which explained the experimental results obtained for three different feedstock oils with ⩾98% accuracy. The rate constants (k), activation energies (Ea) and equilibrium constants (Keq) of the individual reactions were determined by regression analysis which confirmed that the reaction steps were kinetically controlled and not limited by inter-particle diffusion or external mass transfer limitations (Ea > 25 kJ mol−1). Furthermore, the composition feedstock was found to have a distinct effect on the solubility of methanol and oil phase which influenced k, Keq and Ea values, eventually determining the final biodiesel (FAME) yield. To account for the loss of activity upon catalyst reuse, a deactivation model was also proposed which explained our results with ∼94% accuracy. In fact, the loss of activity was accounted for by incorporating a concentration-independent ‘deactivation constant’ kd in the reaction rate equations. Moreover, under optimized reaction conditions (120 °C and 20:1 methanol-to-FFA molar ratio), FAME yields up to 79–91 wt% could be obtained in one step process from oils containing 21–41 wt% FFA.
24.	Kramb, Jason, et al. (författare) Elimination of arsenic-containing emissions from gasification of chromated copper arsenate wood 2016 Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 181, s. 319-324 Tidskriftsartikel (refereegranskat)abstract The behavior of arsenic in chromated copper arsenate containing wood during gasification was modeled using thermodynamic equilibrium calculations. The results of the model were validated using bench-scale gasification tests. It is shown that over 99.6% of arsenic can be removed from the product gas by a hot filter when the gas is cooled below the predicted condensation temperature.
25.	Li, Jun, et al. (författare) Characterization of high-temperature rapid char oxidation of raw and torrefied biomass fuels 2015 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 143, s. 492-498 Tidskriftsartikel (refereegranskat)abstract The promising properties of torrefied biomass provide a valid co-firing option for large percentage biomass utilization in existing coal-fired boilers. Torrefied biomass is expected to have a better combustion stability than raw biomass and similar to that of coal. The present work will characterizes the oxidation properties of torrefied biomass char and compare with that of raw biomass char. The studied two chars are produced from raw and torrefied biomass in an Isothermal Plug Flow Reactor (IPFR) at high temperature and high heating rate, a sufficient residence time is applied for the completion of the high temperature devolatilization. Char oxidation tests are carried out in the IPFR by varying temperature, oxygen concentration and residence time. The reactivity of two studied chars are analyzed and compared with referenced biomass char and coal char, and the impact of torrefaction on char reactivity is also discussed in this paper. Finally, the char oxidation kinetic parameters are determined using a parameter optimization method, and the obtained kinetics are examined by comparing the experimental and predicted mass conversions.

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