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1.	Ahmadi, Mozhgan, et al. (författare) Development of a PID based on-line tar measurement method : Proof of concept 2013 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 113, s. 113-121 Tidskriftsartikel (refereegranskat)abstract In this study, a proof of concept was conducted for an on-line tar analyzer based on photo ionization detection (PID). Tar model compounds (naphthalene, acenaphthene, acenaphthylene, fluorene, indane and indene) were used for the initial investigation of the analysis method. It was found that the analysis method has a high sensitivity and a linear behavior was observed between the PID response and the tar concentration over a wide concentration span. The on-line tar analysis method was successfully validated against the solid phase adsorption (SPA) method using a real producer gas.
2.	Andersson, Robert, et al. (författare) Effect of CO2 in the synthesis of mixed alcohols from syngas over a K/Ni/MoS2 catalyst 2013 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 107, s. 715-723 Tidskriftsartikel (refereegranskat)abstract An unsupported K-Ni-MoS2 catalyst for higher alcohol synthesis from syngas (H-2/CO) has been studied during 360 h on stream. It shows a gradual increase in activity with time on stream and some possible reasons for this are discussed in the paper. The main focus of this paper was to study the on the effect of CO2-containing syngas, relative CO2-free syngas under identical reaction conditions and identical inlet H-2 and CO partial pressures (340 degrees C, 100 bar, GHSV = 6920 ml/(g(cat) h)). The effect of increased partial pressure of H-2 and CO was also studied, and to a minor extent also the effect of changed gas hourly space velocity (GHSV). Under the studied conditions, addition of CO2 was found to greatly decrease total product yield, while the selectivities to alcohol and hydrocarbons (C%, CO2-free), respectively, were unchanged. CO2 addition, however, led to a great change in the distribution within the alcohol and hydrocarbon groups. With CO2 added the methanol selectivity increased much while selectivity to longer alcohols decreased. For hydrocarbons the effect is the same, the selectivity to methane is increased while the selectivity to longer hydrocarbons is decreased. It has earlier been shown that product selectivities are greatly affected by syngas conversion level (correlated to outlet concentration of organic products, i.e. alcohols, hydrocarbons etc.) which can be altered by changes in space velocity or temperature. This means that alcohol selectivity is decreased in favor of increased hydrocarbon selectivity and longer alcohol-to-methanol ratio when syngas conversion is increased. At first it might be thought that the selectivity changes occurring when CO2 is present in the feed, just correlate to a decreased organic product concentration in the reactor and that the selectivities with CO2-containing and CO2-free syngas would be identical under constant concentration of organic products in the reactor. However, CO2-addition studies where space velocity was varied showed that significantly lower alcohol selectivity (mainly ethanol selectivity) and increased hydrocarbon selectivity (mainly methane) were found at similar organic outlet concentrations as when CO2-free syngas was feed. Comparing addition of extra H-2 or extra CO, it was found that a high H-2/CO ratio (H-2/CO = 1.52 tested in our case) favors maximum product yield, especially methanol formation, while a lower H-2/CO ratio (H-2/CO = 0.66 tested in our case) leads to higher yield of higher alcohols simultaneously minimizing hydrocarbon and methanol formation.
3.	Andersson, Robert, et al. (författare) Higher alcohols from syngas using a K/Ni/MoS2 catalyst : Trace sulfur in the product and effect of H2S-containing feed 2014 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 115, s. 544-550 Tidskriftsartikel (refereegranskat)abstract Two types of experiments have been performed related to the higher alcohol synthesis from syngas over a K-Ni-MoS2 catalyst which beforehand has been operated for 1000 h on stream in sulfur-free syngas. In the first experimental part, sulfur-free syngas was used as feed and the condensed liquid product was found to contain 67 ppmw sulfur, while the sulfur concentration in the gas was 19 ppmv. The gas phase was found to contain mainly COS and H2S, while the liquid phase contained methanethiol (13.8 ppmw S), ethanethiol (10.6 ppmw S), dimethyl sulfide (21.3 ppmw S), ethyl methyl sulfide (12.2 ppmw S), unidentified sulfur compounds (7.9 ppmw S) together with some dissolved COS (0.5 ppmw S) and H2S (1.2 ppmw S). In the second experimental part, the effect of feeding syngas containing 170 ppm H2S compared to a sulfur-free syngas was studied, while all products were carefully monitored online. The presence of H2S in the syngas was found to increase CO conversion, but the largest change was found in product selectivity. The hydrocarbon selectivity greatly increased at the expense of alcohol selectivity, while the alcohol distribution shifted towards longer alcohols (increased C2+OH/MeOH ratio). From product yields it became clear that most of the increased CO conversion with H2S in the feed was due to increased methane formation (and CO2 formation due to the water-gas shift reaction). The presence of H2S in the feed greatly increased the concentration of all sulfur compounds. Together with COS, formation of thiols (methanethiol and ethanethiol) was especially favored by the presence of H2S. The thioether concentration also increased, however, to a much lower extent.
4.	Bjurström, Henrik, et al. (författare) Unburned carbon in combustion residues from solid biofuels 2014 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 117:Part A, s. 890-899 Tidskriftsartikel (refereegranskat)abstract Unburned carbon (UC) in 21 combustion residues from solid biofuels has been examined using several methods of analysis (including LOI and TOC) as well as micro-Raman spectroscopy. The concentration of unburned carbon in the residues varied over an order of magnitude and in several samples accounted for about 10% of the ash mass. It was observed that TOC had a poor correlation to organic carbon, especially for fly ashes. LOI at all tested temperatures showed a better correlation than TOC to the organic carbon content, whereas the TOC is better correlated to elemental carbon. LOI550 gave a larger variation and a less complete mobilisation of unburned carbon than LOI at 750 or 975 °C did, but at the highest temperature metal oxidation was notably affecting the mass balance to the extent that some samples gained mass. For this reason, and of the temperatures tested, LOI750 seem to be the most stable indicator for organic remains in the incineration residuals. Most of the unburned carbon is elemental, and only slowly degradable, so the potential emissions of organic compounds from ashes should not be assessed by using a TOC test. The structure of the detected elemental carbon in UC is similar to that of activated carbon, which indicates a potentially large specific surface. This should be borne in mind when assessing the environmental impact of using ash for different purposes, including use as a construction material. Field studies are needed to verify the actual impact as it may depend on environmental conditions.
5.	Cardozo Rocabado, Evelyn, et al. (författare) Combustion of agricultural residues : An experimental study for small-scale applications 2014 Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 115, s. 778-787 Tidskriftsartikel (refereegranskat)abstract Energy services could be greatly improved by using of residues from local food industries in small-scale combustion units. Wood pellets are a reliant and proven fuel to be used in small-scale combustion units. However, these units should preferably be able to use different types of biomass depending what it is locally available. Therefore, studies have been focused on exploring the suitability of using agricultural residues for small-scale heat and power generation using direct combustion. This study targets to compare the combustion of different agricultural residues in a single unit designed for wood pellets. The different biomass fuels used are circle divide 6 mm and circle divide 8 mmwood pellets, circle divide 6 mmbagasse pellets, circle divide 6 mmsunflower husk (SFH) pellets and Brazil nut (BN) shells. The results reveal a decrease in the fuel power input, higher oxygen levels in the flue gases and shorter cycles for ash removal when using the agricultural residues. The excess air ratio was calculated based on a mass balance and compared with a standard equation showing a good agreement. CO and NO emission levels as well as the relative conversion of fuel-C to CO were higher for the BN shells and SFH pellets in comparison to the other biomass types. SO2 emission was estimated based on the analysis of unburned sulfur in ash and mass balances; the higher estimated levels corresponded to the BN shells and SFH pellets. All the biomass sorts presented over 95% relative conversion of fuel-C to CO2. Wood pellets and BN shells presented the highest amount of unburned carbon in ash relative to the fuel-C. The relative conversion of fuel-N to NO and fuel-S to SO2 were higher for wood pellets. Bagasse pellets showed similar emission levels and relative conversion efficiency to wood pellets.
6.	Carlsson, Per, et al. (författare) Experimental investigation of an industrial scale black liquor gasifier : 1. Influence of reactor operation parameters on product gas composition 2010 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 89:12, s. 4025-4034 Tidskriftsartikel (refereegranskat)abstract A novel technology to mitigate the climate changes and improve energy security is Pressurized Entrained flow High Temperature Black Liquor Gasification (PEHT-BLG) in combination with an efficient fuel synthesis using the resulting syngas. In order to optimise the technology for use in a pulp and paper mill based biorefinery, it is of great importance to understand how the operational parameters of the gasifier affect the product gas composition. The present paper is based on experiments where gas samples were withdrawn from the hot part of a 3 MW entrained flow pressurized black liquor gasifier of semi industrial scale using a high temperature gas sampling system. Specifically, the influence of process conditions on product gas composition (CO2, CO, H2, CH4, H2S, and COS) were examined by systematically varying the operational parameters: system pressure, oxygen to black liquor equivalence ratio, black liquor flow rate to pressure ratio and black liquor pre-heat temperature. Due to the harsh environment inside the gasification reactor, gas sampling is a challenging task. However, for the purpose of the current study, a specially designed high temperature gas sampling system was successfully developed and used. The results, obtained from two separate experimental campaigns, show that all of the investigated operational parameters have a significant influence on the product gas composition and present valuable information about to the process characteristics.
7.	Chartier, Clement, et al. (författare) Influence of jet-jet interactions on the lift-off length in an optical heavy-duty DI diesel engine 2013 Ingår i: Fuel. - : Elsevier BV. - 1873-7153 .- 0016-2361. ; 112, s. 311-318 Tidskriftsartikel (refereegranskat)abstract Several investigations have reported that the lift-off length on diesel jets depends strongly on the ambient temperature. The spacing between adjacent jets is thereby expected to influence the lift-off length, as it affects the amount of hot, burned gases present between the jets. Measurements on an 8-hole nozzle in an optical diesel engine showed that the lift-off length can be transient at all times between the start and end of injection. This is attributed to varying in-cylinder temperature and especially to the presence of hot combustion products in the gases entrained into the jets. The effect of inter-jet angle on lift-off length was investigated using symmetric and asymmetric nozzle cups. Decreasing the inter-jet angle produces shorter lift-off length. The lift-off length showed a weaker dependence on the ambient temperature in the engine than predicted by an empirical expression established in a constant-volume combustion vessel. These findings indicate that experiments in such vessels may not capture all features of the conditions in engines. The lift-off length tended to be 15% shorter on the downswirl (leeward) side of the jet. A strong interaction between the effects of the inter-jet spacing and the inlet temperature on the lift-off length was found. All these effects are attributed to the presence of hot gases between the jets. (C) 2013 Elsevier Ltd. All rights reserved.
8.	Dirrenberger, P., et al. (författare) Laminar burning velocity of gasolines with addition of ethanol 2014 Ingår i: Fuel. - : Elsevier BV. - 1873-7153 .- 0016-2361. ; 115, s. 162-169 Tidskriftsartikel (refereegranskat)abstract The adiabatic laminar burning velocities of a commercial gasoline and of a model fuel (n-heptane, iso-octane, and toluene mixture) of close research octane number have been measured at 358 K. Non-stretched flames were stabilized on a perforated plate burner at 1 atm. The heat flux method was used to determine burning velocities under conditions for which the net heat loss of the flame is zero. Very similar values of flame velocities have been obtained for the commercial gasoline and for the proposed model fuel. The influence of ethanol as an oxygenated additive has been investigated for these two fuels and has been found to be negligible for values up to 15% (vol). Measurements were also performed for ethanol and the three pure components of the model fuel at 298, 358 and 398 K. The results obtained for the studied mixtures, and for pure n-heptane, iso-octane, toluene and ethanol, have been satisfactorily simulated using a detailed kinetic mechanism. (C) 2013 Elsevier Ltd. All rights reserved.
9.	Duwig, Christophe, et al. (författare) Large Eddy Simulation of turbulent combustion in a stagnation point reverse flow combustor using detailed chemistry 2014 Ingår i: Fuel. - : Elsevier BV. - 1873-7153 .- 0016-2361. ; 123, s. 256-273 Tidskriftsartikel (refereegranskat)abstract For meeting stringent emission restrictions, a modern solution is to operate in or close to the flameless mode. It implies a copious dilution of the reactants with vitiated gas resulting in low oxidant or fuel concentration and consequently low volumetric heat-release rate. On the contrary to traditional flames where heat release is occurring in very thin fronts, the flameless operation lies in the distributed reaction regime. Flameless operation is therefore associated with complex and non-linear interaction between mixing and chemical reactions. In this framework, this paper investigates turbulent combustion in a stagnation point reverse flow combustor and presents one of the first studies combining Large Eddy Simulation and detailed chemistry for capturing the reaction and flow dynamics during flameless combustion. The paper reports a comprehensive sensitivity analysis where the effects of the numerical discretization grid, of the chemical mechanism, of the operation (premixed vs. non-premixed) and of the heat-losses at the walls are studied and compared. Further, the simulation results are compared with experimental data from the literature, giving confidence in the quality of the predictions. The reaction and flow dynamics are extracted from the results using modal analysis, showing rotational and helical structures. Finally, the distribution of intermediate species in the reaction layer is investigated bringing some new insights into the flameless combustion process and providing recommendations for further experimental investigations. (C) 2014 Elsevier Ltd. All rights reserved.
10.	Eriksson, Gunnar, et al. (författare) Combustion and fuel characterisation of wheat distillers dried grain with solubles (DDGS) and possible combustion applications 2012 Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 102, s. 208-220 Tidskriftsartikel (refereegranskat)abstract The present transition to a sustainable global energy system requires that biomass is increasingly combusted for heat and power production. Agricultural fuels considered include alkali-rich fuels with high phosphorus content. One such fuel is wheat distiller’s dried grain with solubles (wheat DDGS) from wheat-based ethanol production. Further increases in ethanol production may saturate the current market for wheat DDGS as livestock feed, and fuel uses are therefore considered. Fuel properties of wheat DDGS have been determined. The ash content (5.4 ± 1.6 %wt d.s.) is similar to many agricultural fuels. In comparison to most other biomass fuels the sulphur content is high (0.538 ± 0.232 %wt d.s.), and so are the contents of nitrogen (5.1 ± 0.6 %wt d.s.), phosphorus (0.960. ± 0.073 %wt d.s.) and potassium (1.30 ± 0.35 %wt d.s.). To determine fuel-specific combustion properties, wheat DDGS and mixes between wheat DDGS and logging residues (LR 60 %wt d.s. and DDGS 40 %wt d.s.), and wheat straw (wheat straw 50 %wt d.s., DDGS 50 %wt d.s.) were pelletized and combusted in a bubbling fluidised bed combustor (5 kW) and in a pellets burner combustor (20 kW). Pure wheat DDGS powder was also combusted in a powder burner (150 kW). Wheat DDGS had a high bed agglomeration and slagging tendency compared to other biomass fuels, although these tendencies were significantly lower for the mixture with the Ca-rich LR, probably reflecting the higher first melting temperatures of K–Ca/Mg-phosphates compared to K-phosphates. Combustion and co-combustion of wheat DDGS resulted in relatively large emissions of fine particles (<1 μm) for all combustion appliances. For powder combustion PMtot was sixteen times higher than from softwood stem wood. While the Cl concentrations of the fine particles from the the mixture of LR and wheat DDGS in fluidised bed combustion were lower than from combustion of pure LR, the Cl- and P-concentrations were considerably higher from the wheat DDGS mixtures combusted in the other appliances at higher fuel particle temperature. The particles from powder combustion of wheat DDGS contained mainly K, P, Cl, Na and S, and as KPO3 (i.e. the main phase identified with XRD) is known to have a low melting temperature, this suggests that powder combustion of wheat DDGS should be used with caution. The high slagging and bed agglomeration tendency of wheat DDGS, and the high emissions of fine particles rich in K, P and Cl from combustion at high temperature, mean that it is best used mixed with other fuels, preferably with high Ca and Mg contents, and in equipment where fuel particle temperatures during combustion are moderate, i.e. fluidised beds and possibly grate combustors rather than powder combustors.
11.	Gonzalez, Angelica V., et al. (författare) Autothermal reforming of Fischer-Tropsch diesel over alumina and ceria-zirconia supported catalysts 2013 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 107, s. 162-169 Tidskriftsartikel (refereegranskat)abstract Autothermal reforming (ATR) of synthetic Fischer-Tropsch diesel has been carried out to evaluate the fuel reformer and the catalyst performance at realistic operating conditions. Hydrogen was produced via ATR in a full-scale reformer (ID = 84 mm, L = 400 mm) at 650-750 degrees C. The two monolithic catalysts were sequentially located in the reformer and simultaneously tested. The catalysts were composed of 1:1 wt% Rh:Pt as active metals; CeO2, MgO, Y2O3, and La2O3 were used as promoters. The first catalytic monolith was supported on delta-Al2O3 and the second on CeO2-ZrO2. Fresh samples were characterized by N-2-BET, XRD and H-2-TPR analyses. Catalyst activity was evaluated at O-2/C similar to 0.34-0.45 and H2O/C similar to 2-3. Results show an increased catalyst activity after the second monolithic catalyst due to the effect of steam reforming, water-gas shift reaction (WGS) and higher catalyst reducibility of RhxOy species on the CeO2-ZrO2 mixed oxide as a result of the improved redox properties. Hydrogen concentrations of 42 vol% and fuel conversion of 98% after the CeO2-ZrO2-supported catalyst was obtained at O-2/C = 0.42 and H2O/C = 2.5.
12.	Granström, Karin, 1974- (författare) Sawdust age affect aldehyde emissions in wood pellets 2014 Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 126, s. 219-223 Tidskriftsartikel (refereegranskat)abstract The environmental and energy policies in most nations worldwide aim at replacing fossil fuels with renewable sources of energy. The use of wood pellets made from sawdust is rapidly increasing. Wood pellets are a refined compacted fuel with high energy density and low emissions during combustion. Sawdust and wood pellets may be stored for several months due to seasonal demand variation and wood-fuel trade. Wood contains unsaturated fatty acids susceptible to oxidation, a process commonly referred to as fats going rancid. The level of oxidation in pellets is an important parameter of pellets quality as oxidation during storage causes problems such as self-ignition of pellets stored in silos and emissions of malodorous compounds. The purpose of this work was to investigate the effect of the age of the raw material on the oxidation caused aldehyde emissions from wood pellets. Pellets were produced from Scots pine (Pinus sylvestris) sawdust that was either freshly sawn or had been stored for 4 months. The pellets were then stored in either 18 °C or in 40 °C. The formation of the aldehyde hexanal was analyzed with static headspace and gas chromatography. Pellets made from fresh sawdust were low-emitting after 80 days, whereas pellets made from aged sawdust did not reach the same low level until 190 days after production. This held true whether the pellets were stored in 18 °C or in 40 °C. The aged sawdust pellets had maximum emissions at the same time as the emissions ceased from the fresh sawdust pellets. A key conclusion is that when a low level of aldehyde emissions is required during storage, the pellets should be produced of sawdust that is freshly sawn.
13.	Göransson, Kristina, et al. (författare) Experimental test on a novel dual fluidised bed biomass gasifier for synthetic fuel production 2011 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 90:4, s. 1340-1349 Tidskriftsartikel (refereegranskat)abstract This article presents a preliminary test on the 150 kWth allothermal biomass gasifier at MIUN (Mid Sweden University) in Härnösand, Sweden. The MIUN gasifier is a combination of a fluidised bed gasifier and a CFB riser as a combustor with a design suitable for in-built tar/CH4 catalytic reforming. The test was carried out by two steps: 1) fluid-dynamic study; 2) measurements of gas composition and tar. A novel solid circulation measurement system which works at high bed temperatures is developed in the presented work. The results show the dependency of bed material circulation rate on the superficial gas velocity in the combustor, the bed material inventory and the aeration of solids flow between the bottoms of the gasifier and the combustor. A strong influence of circulation rate on the temperature difference between the combustor and the gasifier was identified. The syngas analysis showed that, as steam/biomass (S/B) ratio increases, CH4 content decreases and H2/CO ratio increases. Furthermore the total tar content decreases with increasing steam/biomass ratio and increasing temperature. The biomass gasification technology at MIUN is simple, cheap, reliable, and can obtain a syngas of high CO+H2concentration with sufficient high ratio of H2 to CO, which may be suitable for synthesis of Methane, DME, FT-fuels or alcohol fuels. The measurement results of MIUN gasifier have been compared with other gasifiers. The main differences can be observed in the H2 and the CO content, as well as the tar content. These can be explained by differences in the feed systems, operating temperature, S/B ratio or bed material catalytic effect etc..
14.	Happonen, Matti, et al. (författare) The comparison of particle oxidation and surface structure of diesel soot particles between fossil fuel and novel renewable diesel fuel 2010 Ingår i: Fuel. - : Elsevier BV. - 1873-7153 .- 0016-2361. ; 89:12, s. 4008-4013 Tidskriftsartikel (refereegranskat)abstract Conventional fossil diesel fuel and renewable diesel fuel based on hydrotreated vegetable oils (HVO) were compared regarding the oxidation characteristics of the generated soot particulate. The comparison was performed by utilizing a high-temperature oxidation tandem differential mobility analyser in which monodisperse soot aerosol was first selected and then heated in a high-temperature furnace. The particle size reduction caused by oxidation during the furnace treatment was then measured as a function of furnace temperature. The results indicate that soot oxidation is very similar between the studied fuels. This is supported by the obtained HR-TEM images and EELS-spectra which were practically indistinguishable between different fuels and engine conditions. The similar oxidation properties and surface structure between fossil and HVO-based diesel fuels imply that the oxidative aftertreatment devices designed for fossil diesel should work well also with the studied renewable diesel fuel. (C) 2010 Elsevier Ltd. All rights reserved.
15.	He, Yong, et al. (författare) Investigation of laminar flame speeds of typical syngas using laser based Bunsen method and kinetic simulation 2012 Ingår i: Fuel. - : Elsevier BV. - 1873-7153 .- 0016-2361. ; 95:1, s. 206-213 Tidskriftsartikel (refereegranskat)abstract Synthetic gas (syngas) fuels are promising energy sources in the future. In the current work, laminar flame speeds of typical syngas with different H-2 contents were studied using both experimental measurements and kinetic simulations. Measurements were carried out using the Bunsen method with the flame area derived from the OH planar laser-induced fluorescence (OH-PLIF) images; while kinetic simulations were made using CHEMKIN with two mechanisms: GRI-Mech 3.0 and USC-Mech II. The OH-PLIF based Bunsen method was validated with previous results. Both the experimental and simulated results indicated that the flame speed of syngas increased with H-2 concentration, which, based on the simulation, is attributed to the rapid production of highly reactive radicals and the acceleration of chain-branching reactions by these radicals. In general, predictions with both mechanisms agreed well with measurements, especially for fuel-lean conditions; simulations with USC-Mech II gave better agreement with experimental results at Phi = 0.8 and 0.9 (discrepancy <5%). (C) 2011 Elsevier Ltd. All rights reserved.
16.	Heimdal Nilsson, Elna, et al. (författare) Laminar burning velocities of acetone in air at room and elevated temperatures 2013 Ingår i: Fuel. - : Elsevier BV. - 1873-7153 .- 0016-2361. ; 105, s. 496-502 Tidskriftsartikel (refereegranskat)abstract Laminar burning velocities of acetone + air mixtures at initial gas mixture temperatures of 298, 318, 338 and 358 K are reported. Non-stretched flames were stabilized on a perforated plate burner at 1 atm, and laminar burning velocities were determined using the heat flux method, at conditions where the net heat loss from the flame to the burner is zero. The overall accuracy of the burning velocities was estimated to be better than +/- 1.0 cm s (1). Very good reproducibility of the results and excellent agreement with modeling using a recently updated chemical kinetic model brings confidence in the validity of the reported results. Previous determinations of laminar burning velocities for acetone have provided inconsistent results. In the present work it is suggested that this can in part be attributed to the chemically aggressive nature of acetone. (C) 2012 Elsevier Ltd. All rights reserved.
17.	Höök, Mikael, 1982- (författare) Depletion rate analysis of fields and regions : a methodological foundation 2014 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 121:4, s. 95-108 Tidskriftsartikel (refereegranskat)abstract This paper presents a comprehensive mathematical framework for depletion rate analysis and ties it to the physics of depletion. Theory was compared with empirical data from 1036 fields and a number of regions. Strong agreement between theory and practice was found, indicating that the framework is plausible. Both single fields and entire regions exhibit similar depletion rate patterns, showing the generality of the approach. The maximum depletion rates for fields were found to be well described by a Weibull distribution.Depletion rates were also found to strongly correlate with decline rates. In particular, the depletion rate at peak was shown to be useful for predicting the future decline rate. Studies of regions indicate that a depletion rate of remaining recoverable resources in the range of 2–3% is consistent with historical experience. This agrees well with earlier “peak oil” forecasts and indicates that they rest on a solid scientific ground.
18.	Höök, Mikael, 1982-, et al. (författare) Global coal production outlooks based on a logistic model 2010 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 89:11, s. 3546-3558 Tidskriftsartikel (refereegranskat)abstract A small number of nations control the vast majority of the world’s coal reserves. The geologically available amounts of coal are vast, but geological availability is not enough to ensure future production since economics and restrictions also play an important role. Historical trends in reserve and resource assessments can provide some insight about future coal supply and provide reasonable limits for modelling. This study uses a logistic model to create long-term outlooks for global coal production. A global peak in coal production can be expected between 2020 and 2050, depending on estimates of recoverable volumes. This is also compared with other forecasts. The overall conclusion is that the global coal production could reach a maximum level much sooner than most observers expect.
19.	Ilieva, L., et al. (författare) Pure hydrogen production via PROX over gold catalysts supported on Pr-modified ceria 2014 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 134, s. 628-635 Tidskriftsartikel (refereegranskat)abstract Two series of Pr-doped (5 and 10 at.% Pr) cerium oxides were synthesized by impregnation (IM) and microemulsion method (ME). The Au catalysts (3 wt.%) supported on these oxides were tested in PROX. The samples were characterized by XRD, XPS and TPR measurements. At the operating temperature of the fuel cells (80-120 degrees C) gold catalysts on Pr-doped ceria supports synthesized by IM method exhibited much higher PROX activity as compared to the case of ME method. The observed different catalytic behavior was attributed to the different support preparation affecting the gold particle sizes and the mixed support features. In the case of mixed supports synthesized by IM the size of gold particles established by XRD is smaller and the supply of oxygen evidenced by the obtained TPR results is higher as compared to the gold catalysts on the ME prepared mixed supports. The higher gold dispersion as well as the more defective structure assumed by higher microstrain parameter of ceria lattice (XRD data) due to Pr-doping by IM method, improved both the reducibility and the PROX activity up to 120 degrees C.
20.	Jones, Frida, et al. (författare) Occurrence and sources of zinc in fuels 2014 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 117:A, s. 763-775 Tidskriftsartikel (refereegranskat)abstract Several studies have shown that the presence of high amounts of Zn, in addition to other elements, in fuels can be a cause of operational difficulties during combustion due to corrosion and slagging and can also cause environmental and health problems due to emissions. In nature, Zn is an essential micronutrient for humans, animals and plants, but in excessive amounts it becomes toxic. This paper presents a review on the content of Zn in different fuels used in energy conversion systems. Altogether, over 20 different fuels divided among waste, biomass and fossil fuels were studied. The highest amounts of Zn are present in waste-derived fuels, particularly in Tire-Derived Fuel (TDF). In tires, Zn is used as a vulcanizing agent and can reach concentration values of 9600-16,800 mg kg-1DS. Waste Electrical and Electronic Equipment (WEEE) is the second Zn-richest fuel; while on average Zn content is around 4000 mg kg-1DS., values of over 19,000 mg kg-1DS. were also reported. High amounts of Zn, 3000-4000 mg kg-1DS., are also found in municipal solid waste (MSW), sludge with over 2000 mg kg-1DS. on average (some exceptions up to 49,000 mg kg-1DS.), and other waste-derived fuels (over 1000 mg kg-1DS.). Zn can also be found in fossil fuels. In coal, the level of Zn is quite low, on average 100 mg kg-1DS., while higher amounts of Zn were reported for oil shale, with values between 20 and 2680 mg kg-1DS. The content of Zn in biomass is basically determined by its natural occurrence, typically 10-100 mg kg-1DS.
21.	Kantarelis, Efthymios, et al. (författare) Effect of zeolite to binder ratio on product yields and composition during catalytic steam pyrolysis of biomass over transition metal modified HZSM5 2014 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 122, s. 119-125 Tidskriftsartikel (refereegranskat)abstract Catalytic pyrolysis of biomass over metal modified zeolites (multifunctional catalysts) is a very promising route for production of hydrocarbons and less oxygenated liquid feedstock suitable for fuels and/or chemicals. In this work the effect of zeolite to binder ratio (Z/B) of a metal modified HZSM5, on products yields and composition during steam pyrolysis of biomass has been investigated. Increased zeolite content resulted in lower liquid yield and increased coke formation; however, more deoxygenated liquids obtained at higher zeolite loadings. Char yield is not significantly affected by the zeolite content. Declining catalytic activity is observed at longer time on stream because of coke deposition. While acidic function of the catalyst deoxygenates carboxylic acids and carbonyls, metal functions seem to selectively convert phenols and methoxy phenols. Competitive steam adsorption on the acid sites of the zeolite seems to lower the conversion to aromatics. The high availability of acid sites, at higher zeolite loading, increases aromatics concentration exponentially. Increased yields of hydrogenated products have been obtained indicating that the Ni-V/HZSM5 catalyst exhibits some hydrogenation activity.
22.	Kassman, Håkan, 1962, et al. (författare) Measures to reduce chlorine in deposits: Application in a large-scale circulating fluidised bed boiler firing biomass 2011 Ingår i: Fuel. - Amsterdam : Elsevier BV. - 0016-2361 .- 1873-7153. ; 90:4, s. 1325-1334 Tidskriftsartikel (refereegranskat)abstract Combustion of biomass with a high content of alkali (mainly potassium, K) and chlorine (Cl) can result in operational problems including deposit formation and superheater corrosion. Among the measures applied to decrease such problems are co-combustion and the use of additives. The positive effects of these measures are to a large extent either sulphation of the alkali chlorides (KCl) to less corrosive alkali sulphates or capture of alkali from KCl during release of HCl. A test campaign was carried out in a large-scale circulating fluidised boiler fired with biomass where the measures applied were sulphation by ammonium sulphate and co-combustion with peat. Their performance was evaluated by means of several advanced measurement tools including: IACM (on-line measurements of gaseous KCl); a low-pressure impactor (size distribution and chemical composition of extracted fly ash particles) and deposit measurements (chemical composition in collected deposits). The overall performance was better for ammonium sulphate, which significantly lowered KCl in the flue gas. Meanwhile no chlorine was found in the deposits. Only a minor reduction of gaseous KCl was obtained during co-combustion with peat although the chlorine content in the deposits was greatly reduced. These findings were supported by the results from the impactor measurements. (C) 2010 Elsevier Ltd. All rights reserved.
23.	Konnov, Alexander, et al. (författare) Adiabatic laminar burning velocities of CH4 + H2 + air flames at low pressures 2010 Ingår i: Fuel. - : Elsevier BV. - 1873-7153 .- 0016-2361. ; 89:7, s. 1392-1396 Tidskriftsartikel (refereegranskat)abstract Experimental measurements of the adiabatic burning velocity in methane + hydrogen + air flames using the Heat Flux method are presented. The hydrogen content in the fuel was varied from 0 to 20%. Non-stretched flames were stabilized on a perforated plate burner from 20 to 100 kPa. The equivalence ratio was varied from 0.8 to 1.4. Adiabatic burning velocities of CH4 + H-2 + air mixtures were found in good agreement with the literature results at atmospheric pressure. Also low-pressure measurements in CH4 + air flames performed earlier were accurately reproduced. The effects of enrichment by hydrogen on the laminar burning velocity at low pressures have been studied for the first time. Calculated burning velocities using the Konnov mechanism are in satisfactory agreement with the experiments over the entire range of conditions. Pressure dependences of the burning velocities for the three fuels studied could be approximated by an empirical exponential correlation. (C) 2009 Elsevier Ltd. All rights reserved.
24.	Konnov, Alexander (författare) The effect of temperature on the adiabatic laminar burning velocities of CH4-air and H-2-air flames 2010 Ingår i: Fuel. - : Elsevier BV. - 1873-7153 .- 0016-2361. ; 89:9, s. 2211-2216 Tidskriftsartikel (refereegranskat)abstract The effect of temperature on the adiabatic laminar burning velocities of CH4 + air and H-2 + air flames was analyzed. Available measurements were interpreted using correlation S-L = S-LO (T/T-o)(alpha). Particular attention was paid to the variation of the power exponent a with equivalence ratio at fixed ( atmospheric) pressure. Experimental data and proposed empirical expressions for a as a function of equivalence ratio were summarized. They were compared with predictions of detailed kinetic models in methane + air and hydrogen + air flames. Unexpected non-monotonic behavior of alpha was found in rich methane + air flames. Modeling results are further examined using sensitivity analysis to elucidate the reason of particular dependences of the power exponent alpha on equivalence ratio. (C) 2009 Elsevier Ltd. All rights reserved.
25.	Konttinen, Jukka, et al. (författare) Trace element behavior in the fluidized bed gasification of solid recovered fuels : a thermodynamic study 2013 Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 106, s. 621-631 Tidskriftsartikel (refereegranskat)abstract Gasification of biomass and recycled fuels is of particular interest for the efficient production of power and heat. Trace elements present as impurities in the product gas should be removed very efficiently. The objective of this work has been to develop and test thermodynamic models for the reactions of trace elements with chlorine and sulfur in the gasification processes of recycled fuels. In particular, the chemical reactions of trace elements with main thermochemical conversion products, main ash components, and bed and sorbent material are implemented into the model. The possibilities of gas cleaning devices in condensing and removing the trace element compounds are studied by establishing the volatilization tendency of trace element compounds in reducing gases. The results obtained with the model are compared with the measured data of trace elements of gasification experiments using solid recovered fuel as feedstock. Some corresponding studies in the literature are also critically reviewed and compared. The observed discrepancies may be attributed to differences in thermodynamic databases applied and experimental arrangements. The method of removing gaseous trace elements by condensation is already in use in the 160 MWth waste gasification plant in Lahti, Finland.

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