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  • 51.
    Saqnati, Mehri
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Strand, Michael
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Lillieblad, Lena
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Hygroscopic behaviour of aerosol particles emitted from biomass fired grate boilers2005In: Aerosol Science and Technology, ISSN 0278-6826, Vol. 39, no 91, p. 919-930Article in journal (Refereed)
    Abstract [en]

    This study focuses on the hygroscopic properties of submicrometer

    aerosol particles emitted from two small-scale district heating

    combustion plants (1 and 1.5 MW) burning two types of biomass

    fuels (moist forest residue and pellets). The hygroscopic particle

    diameter growth factor (Gf ) was measured when taken from a dehydrated

    to a humidified state for particle diameters between 30–

    350 nm (dry size) using a Hygroscopic Tandem Differential Mobility

    Analyzer (H-TDMA). Particles of a certain dry size all showed

    similar diameter growth and the Gf at RH = 90% for 110/100 nm

    particles was 1.68 in the 1MWboiler, and 1.5 in the 1.5MWboiler.

    These growth factors are considerably higher in comparison to

    other combustion aerosol particles such as diesel exhaust, and are

    the result of the efficient combustion and the high concentration of

    alkali species in the fuel. The observed water uptake could be explained

    using the Zdanovski-Stokes-Robinson (ZSR) mixing rule

    and a chemical composition of potassium salts only, taken from

    ion chromatography analysis of filter and impactor samples (KCl,

    K2SO4, andK2CO3). Agglomerated particles collapsed and became

    more spherical when initially exposed to a moderately high relative

    humidity. When diluted with hot particle-free air, the fractallike

    structures remained intact until humidified in the H-TDMA.

    A method to estimate the fractal dimension of the agglomerated

    combustion aerosol and to convert the measured mobility diameter

    hygroscopic growth to the more useful property volume diameter

    growth is presented. The fractal dimension was estimated to be

    ∼2.5.

  • 52.
    Sefidari, Hamid
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Razmjoo, Narges
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Strand, Michael
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    An experimental study of combustion and emissions of two types of woody biomass in a 12-MW reciprocating-grate boiler2014In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 135, p. 120-129Article in journal (Refereed)
    Abstract [en]

    The gaseous emissions of primary concern from biomass combustion are nitrogen oxides (NOX), carbon monoxide, and various unburned gaseous components. Detailed characterization of the gas in the hot reaction zones is necessary to study the release, formation, and evolution of the gas components. In the present study, gas temperature and concentration were measured in a 12-MWth biomass-fired reciprocating-grate boiler operated with over-fire air and flue-gas recirculation. Temperature measurement was combined with flue gas quenching and sample gas extraction using two water-cooled stainless-steel suction pyrometers. The concentration profiles of O2, NO, and CO were experimentally determined throughout the furnace, and the profile gas temperature was measured in several positions inside the furnace for the two types of woody biomass studied. For both fuels, the gas temperature varied between approximately 450 °C (average primary chamber temperature) and 1200 °C (average secondary chamber temperature). The concentration profiles of CO and O2 suggested no conclusive difference between the two types of biomass. However, the local mean concentrations of NO and NOX emission factors (measured in the stack) were higher for Greenery fuel due to its higher nitrogen content than that of Standard fuel.

  • 53.
    Strand, Michael
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Aerosol formation and effect in biomass combustion and gasification2005Report (Other academic)
  • 54. Strand, Michael
    Effects on CO and particle emissions by fuel sulphur addition in a moving grate boiler fired with forest residues.2005In: Proceedings IFRF Swedish-Finnish Flamedays, 2005, p. 185-192Conference paper (Refereed)
    Abstract [en]

    Increasing the sulphur content in the fuel by has been used in boilers fired with biomass in order to prevent high temperature corrosion. The higher sulphur content can be achieved by mixing with high sulphur fuels, e.g. coal or peat or by adding of various sulphur containing chemicals. An additional effect of increasing the sulphur content is that in some cases the emissions of soot, carbon monoxide (CO) and hydrocarbons have been shown to decrease. This has lead to an increasing interest in using sulphur addition as a method to reduce these emissions in medium sized grate boilers fired with biomass fuels, that for different reasons have problems to reach the legislated limits e.g. for CO emissions. However, there have also been a few reports suggesting that the emissions of fine particles in the submicrometer size range might increase with sulphur addition (Lindau and Skog, 2003). Since medium sized grate boilers often lack efficient devises for fine particle removal, there has been a concern that the positive effects on CO emissions by sulphur addition might be accompanied by enhanced particle emissions. In this study CO and particle emissions from a 7 MW boiler fired with moist forest residues with varying admixtures of elemental sulphur were characterised.

  • 55.
    Strand, Michael
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Fine and ultrafine particles from combustion sourses - investigation with in-situ techniques.2005In: Proceedings of the Nordic Aerosol Society, NOSA, 2005, Gothenburg, Sweden, 2005Conference paper (Refereed)
  • 56.
    Strand, Michael
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    In2O3 particle films as gate material for MISiC-capacitor sensors.2005In: Proceedings of the Nordic Aerosol Society, NOSA, 2005, Gothenburg, Sweden, 2005Conference paper (Refereed)
  • 57.
    Strand, Michael
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Metal distribution in particles from grate combustion of woody fuels.2005In: Proceedings European Aerosol Conference 2005, 2005, p. 365-366Conference paper (Refereed)
  • 58.
    Strand, Michael
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    METHOD FOR SAMPLING OF PARTICLES IN THE PRODUCT GAS AT HIGH TEMPERATURES IN A BIOMASS GASIFIER2008In: 16th European Biomass Conference and Exhibition, 2008, p. 934-936Conference paper (Refereed)
    Abstract [en]

    The objective of this study was to investigate the possibility of using a high-temperature dilution-deposition probe in order to determine the particle concentration and size distribution in the hot product gas from gasification of biomass in a bench scale bubbling fluidized bed gasifier. The results indicated that the dilution probe could be used in order to avoid formation of particulate matter inside the probe from condensing alkali at moderate alkali concentrations in the gas. For use at high concentrations of alkali that may be present during oxygen-steam blown gasification of high ash fuels such as straw, the method needs to be further optimized and refined.

    Keywords: gasification, aerosols

  • 59.
    Strand, Michael
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Nanoparticles as sensing material for selective and stable SiC-FET gas sensors.2005In: Proceedings European Aerosol Conference 2005, 2005, p. 735-Conference paper (Refereed)
  • 60.
    Strand, Michael
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Particle removal in electrostatic precipitators after biomass fired district heating plant.2005In: 14th European Biomass Conference and Exhibition, 2005, Paris, France., 2005Conference paper (Refereed)
  • 61.
    Strand, Michael
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Particulate and CO Emissions from a Moving-Grate Boiler Fired with Sulfur-Doped Woody Fuel2007In: Energy & Fuels, ISSN 0887-0624, Vol. 21, no 6, p. 3653-3659Article in journal (Refereed)
    Abstract [en]

    Particulate and gaseous emissions were studied in a 7 MW moving-grate boiler fired with moist sawmill residues together with varying admixtures of elementary sulfur. The particle number concentration decreased by approximately 25% and the sub-micrometer particle mass concentration increased by approximately 100% as 0.17% (by mass, dry substance) of elementary sulfur was added to the fuel. Sulfur addition also resulted in a shift towards larger particle mean diameters. Elementary analysis indicated that the amount of particle-bound sulfur increased significantly with sulfur addition, probably by favoring the formation of alkali sulfates. CO emissions were reduced by approximately 50% in the measurement period when the sulfur admixture with the fuel was 0.17% or higher. The SO2 concentration measured downstream from the flue gas condenser was below the detection limit when no sulfur was admixed and was approximately 30 ppm when 0.12% elementary sulfur was admixed. Sulfur admixture had no significant effect on the NOx concentration.

  • 62.
    Strand, Michael
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Reduction and oxidation kinetics of Mn3O4/Mg–ZrO2 oxygen carrier particles for chemical-looping combustion2007In: Chemical Engineering Science, ISSN 0009-2509, Vol. 62, no 23, p. 6556-6567Article in journal (Refereed)
    Abstract [sv]

    The kinetics of reduction with methane and oxidation with oxygen of Mn3O4 supported on Mg–ZrO2 prepared by freeze granulation has been investigated. The reactivity experiments were performed in a thermogravimetric analyzer (TGA) using different reacting gas concentrations and temperatures in the range of 1073–1223 K. The oxygen carrier particles showed high reactivity during both reduction and oxidation at all investigated temperatures. An empirical reaction model, which assumes a linear relation between time and conversion, was used to determine the kinetic parameters for reduction and oxidation, with chemical reaction being the main resistance to the reaction. The order of reaction found was 1 with respect to CH4 and 0.65 with respect to O2. The activation energy for the reduction reaction was 119 and for the oxidation reaction. The reactivity data and kinetic parameters were used to estimate the solid inventory in the air and fuel reactor of a CLC system. The optimum solid inventory obtained was at a value of ΔXs=0.4. At these conditions, the recirculation rate of oxygen carrier between air and fuel reactor was per MW of fuel, which could be accomplished in an industrial reactor. The high reactivity of the Mn3O4/Mg–ZrO2 with both methane and oxygen showed that this is a very promising oxygen carrier for CLC.

  • 63.
    Strand, Michael
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    RuO2 and Ru nanoparticles for MISIc-FET gas sensors.2005In: Nanotech 2005 (NSTI), Anaheim, USA, 8-12 May, 2005, p. 269-272Conference paper (Refereed)
    Abstract [en]

    Catalytically active nanoparticles used as gate material on SiC-FET gas sensors. The goal is to improve the selsectivity and senstitivty.The sensors are sensitive towards oxidising and reducing gases (H2, NH3, C3H6).

  • 64.
    Strand, Michael
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Carrasco, Juan
    Centro de Investigaciones Energéticas y Tecnológicas.
    Esteban, Luis
    Centro de Investigaciones Energéticas y Tecnológicas.
    Koch, Thomas
    KT Energi.
    de Jong, Wiebren
    Technische Universiteit Delft.
    Brandin, Jan
    Lunds tekniska högskola.
    Bengtsson, Sune
    LNU.
    Baudin, Anders
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Waldheim, Anders
    Termiska Processer TPS.
    CHRISGAS Intermediate report2008Report (Other academic)
  • 65.
    Strand, Michael
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Gustafsson, Eva
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Final Report on the Recommended General Design andDevelopment of Gas and Aerosol Particle Sampling Probes2010Report (Other academic)
  • 66.
    Strand, Michael
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Gustafsson, Eva
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Lin, Leteng
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Yang, Jingjing
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    High-Temperature extraction of aerosol particles from biomass combustion and gasification2011In: European Aerosol Conference 2011, 2011Conference paper (Refereed)
  • 67.
    Strand, Michael
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Lutic, Doina
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. University of Kalmar, Department of Technology. Bioenergiteknik.
    Sanati, Mehri
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. University of Kalmar, Department of Technology. Bioenergiteknik.
    Catalyst properties of oxide nanoparticles applied in gas sensors manufacturing2006In: 12th Nordic Symposium in Catalysis-May 28-30-Trondheim-Norway, 2006, p. 167-168Conference paper (Other academic)
  • 68.
    Strand, Michael
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Sanati, Mehri
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Bioenergiteknik.
    Fly ash elementary composition in a moving grate boiler fired with sulphur-doped woody fuel2007In: 15th European Biomass Conference and Exhibition, ETA-Renewable Energies and WIP-Renewable Energies , 2007, p. 1468-1469Conference paper (Refereed)
    Abstract [en]

    The elementary composition of fly ash particles in the size range of 0.03-1.64 mm were studied in a 7 MW moving-grate boiler fired with moist sawmill residues together with varying admixtures of elementary sulphur. Size segregated elementary analysis showed that the main elements were K, S, Cl and Zn and that there were no enrichment of any of these elements in any size fraction. When a sulphur admixture of 0.25 % was used the concentration of S increased, and the particles were almost completely depleted of Cl. Sulphur admixture had no significant effect on the concentration or distribution of the trace elements analysed.

  • 69.
    Strand, Michael
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Sanati, Mehri
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Bioenergiteknik.
    Metal oxide nanoparticles as novel gate materials for field-effect gas sensors2006In: Materials and Manufacturing Processes, ISSN 1042-6914, Vol. 21, no 3, p. 275-278Article in journal (Refereed)
    Abstract [en]

    Oxide nanoparticle layers have shown interesting behavior as gate materials for high temperature (typically at 300-400 deg.C) metal-insulator-silicon carbide (MISiC) capacitive sensors. Distinct shifts in the depletion region of the C-V (capacitance-voltage) characteristics could be observed while switching between different oxidizing and reducing gas ambients (air, O 2 , H2 , NH3 , CO, NOx , C3H6 ). Shifts were also noticed in the accumulation region of the C-V curves, which can be attributed to the change in resistivity of the gate material. Sensor response patterns have been found to depend on operating temperature.

  • 70.
    Strand, Michael
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Sanati, Mehri
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Particle emissions from district heating units operating on three commonly used biofuels2005In: Atmospheric Environment, ISSN 1352-2310, Vol. 39, no 1, p. 139-150Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to characterise particle emissions from district heating units operating on three commonly used biofuels: forest residues, pellets and sawdust. Boilers used in the three district heating units were of moving grate type, with the maximum thermal output between 1 and 1.5 MW. The measurements were done after multicyclones, the only particle removal devices installed, therefore the direct emissions to ambient air were characterised. Number and mass size distributions were determined. Elemental composition of the particles was determined by particle induced X-ray emissions analysis (PIXE) and thermal-optical analysis. Particles' morphology was assessed on the basis of transmission electron microscopy (TEM). Total number concentration of emitted particles with aerodynamic diameter smaller than 5 &mu;m (PM5) at medium operation load ranged from 6.3 to 7.7&times;10<sup>7</sup> particles/cm <sub>n</sub><sup>3</sup>, with the slightly higher values from combustion of forest residues. PM5 mass concentration at medium load from low pressure impactor measurements ranged between 51 and 120 mg/m<sub>n</sub><sup>3</sup>, with the highest values from unit operating on forest residues. Both PM5 mass and total number concentrations were dominated by fine mode contributions i.e. particles with aerodynamic diameter smaller than 1 &mu;m (PM1). Elements determined by PIXE (Z&gt;12) contributed to 21-34% of PM1 mass, of which K, S, Cl and Ca contributed to 18-33% of PM1 mass, and Zn, Mn, Fe, Cr, Pb and Cd to 1-3%. Emitted concentrations of heavy metals depended on type of the fuel and operating load. Particulate organic (OC) and elemental (EC) carbon contribution to PM1 ranged from 1-19% and 0-56%, respectively. Particulate OC concentrations strongly depended on the operation load regardless the type of the fuel, while EC concentrations seemed to depend both on load and the type of the fuel. Considering the potential public health implications of the obtained results, further research is needed to carefully assess the impact of particle emissions from biofuels combustion on human health and environment. &copy; 2004 Elsevier Ltd. All rights reserved.

  • 71.
    Yang, Jingjing
    et al.
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Gebremedhin, A.
    Strand, Michael
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Particle characterization at high temperature in a 5 MW moving grate biomass boiler2013In: Proceedings for 21st European Biomass Conference and Exhibition, ETA-Florence Renewable Energies , 2013, p. 1132-1135Conference paper (Refereed)
    Abstract [en]

    The particles and inorganic gaseous compounds from a 5 MW moving grate biomass boiler were characterized at two sampling positions at 1100 °C and 800 °C respectivly. Samples were extracted with high temperature sampling method with primary dilution ratio of 20. For both sampling positions a biomodal mass size distributions were observed, with ultrafine mode at around 70-100 nm and fine mode at 10-30 nm. The increasing concentration of ultrafine particle over time indicates that the alkali deposits in the inner wall of dilution probe re-evaporates and condenses on the ultrafine particles. The elemental analysis and ion ratio of (K+Na)/(Cl+2S) and 4S/O indicates that at 1100°C the main species composted of particulate matter are not only alkali chlorides and alkali sulfates.

  • 72.
    Yang, Jingjing
    et al.
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Gebremedhin, Alemayehu
    Strand, Michael
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Characterization of Particles and Inorganic Vapors through High-Temperature Extraction in a Biomass-Fired Grate Boiler2013In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 10, p. 5915-5922Article in journal (Refereed)
    Abstract [en]

    In this study, a method for sampling particles and inorganic vapors in hot flue gases was examined in laboratory studies and then applied in field measurements. The method included a hot dilution probe, where the dilution ratio can be controlled. The laboratory results indicated that applied flow rates and dilution ratios can be optimized to produce two distinct particle modes in the particle size distribution: one from the original particles and one from the condensing vapors. The field measurements were performed in a moving grate biomass boiler, and the probe was used for sampling at two positions, at 800 and 1100 degrees C. The size distributions and the size-resolved elemental composition of the samples showed that, at 800 degrees C, alkali sulfates had formed a fine particle mass mode at around 100 nm and that alkali chlorides condensed in the probe to form an additional ultrafine mode in the 10-30 nm range. At 1100 degrees C, a similar bimodal size distribution was obtained as for 800 degrees C; however, the particle diameter of the fine mode was lower and the particle mass concentration was about one-third of the mass at 800 degrees C. The elemental analysis of the ultrafine mode sampled at 1100 degrees C indicated that it was formed mainly from condensing alkali sulfates. In addition, the sample contained detectable amounts of Zn. The suggested interpretation of these results was that, at 1100 degrees C, Zn had oxidized to form ZnO particles and that the formation and condensing of alkali sulfates was in progress, while alkali chlorides were present as vapor.

  • 73.
    Yang, Jingjing
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. Gjövik Univ Coll, Norway.
    Lin, Leteng
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Morgalla, Mario
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Gebremedhin, Alemayehu
    Gjövik Univ Coll, Norway.
    Strand, Michael
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    High-Temperature Characterization of Inorganic Particles and Vapors in a Circulating Fluidized Bed Boiler Cofiring Wood and Rubber Waste2015In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 29, no 2, p. 863-871Article in journal (Refereed)
    Abstract [en]

    The effects of varying fuel mixtures and using a lime additive were studied in a 125-MWth circulating fluidized bed boiler. A high-temperature aerosol measurement method using a hot-dilution probe was used to characterize the particles and condensing inorganic vapors upstream from the superheater. The particle size distributions of the extracted samples indicate that when high-sulfur rubber waste, waste wood, and forest fuel were cocombusted, the hot flue gas contained no substantial amount of particulate matter in the fine (<0.3 mu m) particle size range, although the SO2 concentration exceeded 70 ppm. Only a nucleation mode was observed, which was presumably formed from inorganic vapors that condensed in the sampling probe. The size-segregated elemental analysis of the extracted samples indicated that when lime was added, the nucleation mode mainly comprised condensed alkali chlorides, while the sulfates dominated the mode when no lime was added. The presumed explanation for the sulfates in the nucleation mode was the sulfation of the alkali chlorides inside the sampling system. When only the wood fuels and no rubber fuel were cocombusted, the SO2 concentration in the gas was approximately 5 ppm. In this case, an alkali sulfate particle mode formed at approximately 70 nm in the hot flue gas. In addition, vapors of alkali chlorides and lead formed particulate matter inside the sampling probe when using low dilution ratios.

12 51 - 73 of 73
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