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  • 1.
    Carlborg, Markus
    et al.
    Umeå University, Sweden.
    Weiland, Fredrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Ma, Charlie
    Luleå University of Technology, Sweden.
    Backman, Rainer
    Umeå University, Sweden.
    Landälv, Ingvar
    Luleå University of Technology, Sweden.
    Winikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center. Luleå University of Technology, Sweden.
    Exposure of refractory materials during high-temperature gasification of a woody biomass and peat mixture2018In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 38, no 2, p. 777-787Article in journal (Refereed)
    Abstract [en]

    Finding resilient refractory materials for slagging gasification systems have the potential to reduce costs and improve the overall plant availability by extending the service life. In this study, different refractory materials were evaluated under slagging gasification conditions. Refractory probes were continuously exposed for up to 27 h in an atmospheric, oxygen blown, entrained flow gasifier fired with a mixture of bark and peat powder. Slag infiltration depth and microstructure were studied using SEM EDS. Crystalline phases were identified with powder XRD. Increased levels of Al, originating from refractory materials, were seen in all slags. The fused cast materials were least affected, even though dissolution and slag penetration could still be observed. Thermodynamic equilibrium calculations were done for mixtures of refractory and slag, from which phase assemblages were predicted and viscosities for the liquid parts were estimated. © 2017 Elsevier Ltd

  • 2.
    Carlsson, Per
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Gebart, Rikard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Gronberg, C.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Marklund, Magnus
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Risberg, M.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Öhrman, Olov .G.W
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Spatially resolved measurements of gas composition in a pressurised black liquor gasifier2009In: Environmental Progress & Sustainable Energy, ISSN 1944-7442, E-ISSN 1944-7450, Vol. 28, no 3, p. 316-323Article in journal (Refereed)
    Abstract [en]

    Black liquor gasification is a new process for recovery of energy and chemicals in black liquor from the Kraft pulping process. The process can be combined with catalytic conversion of syngas into motor fuels. The potential for motor fuel production from black liquor in Sweden is to replace about 25% of the current consumption ofgasoline and diesel. For Finland the figure is even higher while for Canada it is about 14% and for the USA about 2%. © 2009 American Institute of Chemical Engineers Environ Prog, 28: 316-323, 2009.

  • 3. Carlsson, Per
    et al.
    Lycksam, H.
    Gren, P.
    Gebart, Rikard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Iisa, K.
    High-speed imaging of biomass particles heated with a laser2013In: Journal of Analytical and Applied Pyrolysis, 2013, Vol. 103, p. 278-286Conference paper (Refereed)
    Abstract [en]

    In this work two types of lignocellulosic biomass particles, European spruce and American hardwood (particle sizes from 100 μm to 500 μm) were pyrolysed with a continuous wave 2 W Nd:YAG laser. Simultaneously a high-speed camera was used to capture the behavior of the biomass particle as it was heated for about 0.1 s. Cover glasses were used as a sample holder which allowed for light microscope studies after the heating. Since the cover glasses are not initially heated by the laser, vapors from the biomass particle are quenched on the glass within about 1 particle diameter from the initial particle. Image processing was used to track the contour of the biomass particle and the enclosed area of the contour was calculated for each frame.

    The main observations are: There is a significant difference between how much surface energy is needed to pyrolyses the spruce (about 75% more) compared to the hardwood. The oil-like substance which appeared on the glass during the experiment is solid at room temperature and shows different levels of transparency. A fraction of this substance is water soluble. A brownish coat is seen on the unreacted biomass. The biomass showed insignificant swelling as it was heated. The biomass particle appears to melt and boil at the front that is formed between the laser beam and the biomass particle. The part of the particle that is not subjected to the laser beam seems to be unaffected.

  • 4.
    Carlsson, Per
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Ma, C.
    Molinder, Roger
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Weiland, Fredrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Ohman, M.,
    Öhrman, Olov .G.W
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Slag formation during oxygen-blown entrained-flow gasification of stem wood2014In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 28, no 11, p. 6941-6952Article in journal (Refereed)
    Abstract [en]

    Stem wood powders were fired in a mullite-lined pilot-scale oxygen-blown pressurized entrained-flow gasifier. During repeated campaigns involving increases in fuel load and process temperature, slag formations that eventuated in the blockage of the gasifier outlet were observed. These slags were retrieved for visual and chemical characterization. It was found that the slags had very high contents of Al and, in particular, high Al/Si ratios that suggest likely dissolution of the mullite-based refractory of the gasifier lining due to interactions with the fuel ash. Possible causes for the slag formation and behavior are proposed, and practical implications for the design of future stem wood entrained-flow gasifiers are also discussed.

  • 5.
    Carlsson, Per
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Marklund, M.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Gebart, Rikard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Comparison and validation of gas phase reaction schemes for black liquor gasification modeling2008In: AIChE Annual Meeting, Conference Proceedings, 2008Conference paper (Refereed)
  • 6.
    Carlsson, Per
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Marklund, Magnus
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Furusjö, Erik
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Gebart, Rikard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Black liquor gasification: CFD model predictions compared with measurements2010In: International Chemical Recovery Conference, 2010, Vol. 2, p. 160-171Conference paper (Refereed)
  • 7.
    Carlsson, Per
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Marklund, Magnus
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Furusjö, Erik
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Gebart, Rikard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Experiments and mathematical models of black liquor gasification: Influence of minor gas components on temperature, gas composition, and fixed carbon conversion2010In: TAPPI Journal, ISSN 0734-1415, Vol. 9, no 9, p. 15-24Article in journal (Refereed)
    Abstract [en]

    In this work, predictions from a reacting Computational Fluid Dynamics (CFD) model of a gasification reactor are compared to experimentally obtained data from an industrial pressurized black liquor gasification plant. The data consists of gas samples taken from the hot part of the gasification reactor using a water cooled sampling probe. During the considered experimental campaign, the oxygen-to-black liquor equivalence ratio (λ was varied in three increments, which resulted in a change in reactor temperature and gas composition. The presented numerical study consists of CFD and thermodynamic equilibrium calculations in the considered λ-range using boundary conditions obtained from the experimental campaign. Specifically, the influence of methane concentration on the gas composition is evaluated using both CFD and thermodynamic equilibrium. The results show that the main gas components (H 2, CO, CO2) can be predicted within a relative error of 5% using CFD if the modeled release of H2S and CH4 are specified a priori. In addition, the calculations also show that the methane concentration has large influence on the reactor outlet temperature and final carbon conversion.

  • 8.
    Carlsson, Per
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Marklund, Magnus
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Grönberg, C.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Pettersson, Esbjörn
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Lidman, M.
    Gebart, Rikard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Experimental investigation of an industrial scale black liquor gasifier: Part 1: The effect of a reactor operation parameters on product gas composition2010In: Fuel, Vol. 89, p. 4025-4034Article in journal (Refereed)
  • 9.
    Gebart, Bo Rikard
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Marklund, Magnus
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Carlsson, Per
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Grönberg, C.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Weiland, Fredrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Johansson, Ann-Christine
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Öhrman, Olov
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Recent advances in the understanding of pressurized black liquor gasification.2011In: Cellulose Chemistry and Technology, Vol. 45, p. 521-526Article in journal (Refereed)
  • 10.
    Gebart, Rikard
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Lidman, M.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Holmberg, H.
    Risberg, M.
    Vortex gasification of biomass for CHP and lime kiln fuel2011In: The International Conference on Thermochemical Conversion Science(tcbiomass), 2011Conference paper (Refereed)
  • 11.
    Gebart, Rikard
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Carlsson, Per
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Marklund, Magnus
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Grönberg, C.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Pettersson, Esbjörn
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Lidman, M.
    Influence from varying operating parameters on the syngas composition from a black liquor gasifier.2011In: The International Conference on Thermochemical Conversion Science(tcbiomass), 2011Conference paper (Refereed)
  • 12.
    Grönberg, C.
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Öhman, R.
    Gebart, Rikard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Granberg, G.
    Jönsson, J.
    Trace elements in the syngas during pressurised black liquor gasification2009In: 10th International Conference on Energy for a Clean Environment, 2009Conference paper (Refereed)
  • 13.
    Holmgren, Per
    et al.
    Umeå University, Sweden.
    Wagner, David R.
    Umeå University, Sweden.
    Strandberg, Anna
    Umeå University, Sweden.
    Molinder, Roger
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Umeki, Kentaur
    Luleå University of Technology, Sweden.
    Broström, Markus
    Umeå University, Sweden.
    Size, shape, and density changes of biomass particles during rapid devolatilization2017In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 206, p. 342-351Article in journal (Refereed)
    Abstract [en]

    Particle properties such as size, shape and density play significant roles on particle flow and flame propagation in pulverized fuel combustion and gasification. A drop tube furnace allows for experiments at high heating rates similar to those found in large-scale appliances, and was used in this study to carry out 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 information on particle size and shape transformation. Pine stem wood and wheat straw were milled and sieved to three narrow size ranges, rapidly heated in a drop tube setup, and solid residues were characterized using optical methods. Different shape descriptors were evaluated and a shape descriptor based on particle perimeter was found to give significant information for accurate estimation of particle volume. The optical conversion model developed was proven useful and showed good agreement with conversion measured using 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 monitoring of particle conversion, provided density data has been calibrated.

  • 14.
    Iisa, Kristiina
    et al.
    National Renewable Energy Laboratory, US.
    Johansson, Ann-Christine
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Pettersson, Esbjörn
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    French, Richard
    National Renewable Energy Laboratory, US.
    Orton, Kellene
    National Renewable Energy Laboratory, US.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Chemical and physical characterization of aerosols from fast pyrolysis of biomass2019In: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250XArticle in journal (Refereed)
    Abstract [en]

    Biomass fast pyrolysis vapors contain a significant quantity of persistent aerosols, which can impact downstream processing by e.g. fouling of surfaces and deposition on downstream catalysts. In this study, aerosol concentrations and size distributions were measured by an impactor in two pyrolysis systems, a bench-scale fluidized-bed pyrolyzer and a pilot-scale cyclone pyrolyzer. In both units, the mass-based mode aerosol diameter was approximately 1 μm before aerosol collection devices in cooled vapors of 300–370 K but the number-based median was < 0.1 μm. Aerosols < 1 μm were formed and aerosols > 1 μm deposited during cooling of pyrolysis vapors from 620 to 370 K in the fluidized-bed pyrolysis system. The oil fraction collected from the aerosols constituted approximately 40 wt% of the total oils collected in both systems. Compared to the total collected oil, the oil fraction from the aerosols was enriched in lignin-derived components and anhydrosugars and had lower concentrations of low molecular weight cellulose derived oxygenates, such as hydroxyketones. 

  • 15.
    Johansson, Ann-Christine
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Iisa, Kristiina
    National Renewable Energy Laboratory, USA.
    Sandström, Linda
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Ben, Haoxi
    National Renewable Energy Laboratory, USA.
    Pilath, Heidi
    National Renewable Energy Laboratory, USA.
    Deutch, Steve
    National Renewable Energy Laboratory, USA.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Öhrman, Olov G.W.
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Fractional condensation of pyrolysis vapors produced from Nordic feedstocks in cyclone pyrolysis2017In: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250X, Vol. 123, p. 244-254Article in journal (Refereed)
    Abstract [en]

    Pyrolysis oil is a complex mixture of different chemical compounds with a wide range of molecular weights and boiling points. Due to its complexity, an efficient fractionation of the oil may be a more promising approach of producing liquid fuels and chemicals than treating the whole oil. In this work a sampling system based on fractional condensation was attached to a cyclone pyrolysis pilot plant to enable separation of the produced pyrolysis vapors into five oil fractions. The sampling system was composed of cyclonic condensers and coalescing filters arranged in series. The objective was to characterize the oil fractions produced from three different Nordic feedstocks and suggest possible applications. The oil fractions were thoroughly characterized using several analytical techniques including water content; elemental composition; heating value, and chemical compound group analysis using solvent fractionation, quantitative 13C NMR and 1H NMR and GC x GC − TOFMS. The results show that the oil fractions significantly differ from each other both in chemical and physical properties. The first fractions and the fraction composed of aerosols were highly viscous and contained larger energy-rich compounds of mainly lignin-derived material. The middle fraction contained medium-size compounds with relatively high concentration of water, sugars, alcohols, hydrocarbonyls and acids and finally the last fraction contained smaller molecules such as water, aldehydes, ketones and acids. However, the properties of the respective fractions seem independent on the studied feedstock types, i.e. the respective fractions produced from different feedstock are rather similar. This promotes the possibility to vary the feedstock depending on availability while retaining the oil properties. Possible applications of the five fractions vary from oil for combustion and extraction of the pyrolytic lignin in the early fractions to extraction of sugars from the early and middle fractions, and extraction of acids and aldehydes in the later fractions.

  • 16.
    Johansson, Ann-Christine
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Sandström, Linda
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Öhrman, Olov G.W.
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Experiences of pilot scale cyclone pyrolysis2017In: European Biomass Conf. Exhib. Proc., ETA-Florence Renewable Energies , 2017, no 25thEUBCE, p. 952-955Conference paper (Refereed)
    Abstract [en]

    Fast pyrolysis is a promising thermochemical technology for converting biomass to energy, chemicals, and fuels. At RISE ETC, an industrially relevant pyrolysis pilot plant has been designed, constructed, and operated since 2011. The pilot plant is based on an externally heated cyclone reactor where both the pyrolysis reaction and the separation of products take place. The reactor design has shown to be beneficial since it produces oil with relatively low concentrations of inorganics. Pyrolysis of different Nordic biomasses, both forestry and agricultural, have been studied using the pilot plant and the results indicate that it is especially suitable for low grade fuels. The oil is collected in two separate steps, and the received two oil fractions have different chemical and physical properties, which opens up the possibility to use selected fractions in targeted applications. Oil fractionation has also been studied further in a separate fractional condensation system and the results show that it is possible to separate larger energy-rich lignin-derived material; medium-sized; and light water soluble compounds already in the oil collection step. The pilot plant has worked as a platform for pyrolysis research and for building up competence in the pyrolysis area. 

  • 17.
    Johansson, Ann-Christine
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Sandström, Linda
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Marklund, Magnus
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Öhrman, Olov G. W.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Narvesjö, Jimmy
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Characterization of pyrolysis products produced from different Nordic biomass types in a cyclone pilot plant2016In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 146, p. 9-19Article in journal (Refereed)
    Abstract [en]

    Pyrolysis is a promising thermochemical technology for converting biomass to energy, chemicals and/or fuels. The objective of the present paper was to characterize fast pyrolysis products and to study pyrolysis oil fractionation. The products were obtained from different Nordic forest and agricultural feedstocks in a pilot scale cyclone pyrolysis plant at three different reactor temperatures. The results show that the main elements (C, H and O) and chemical compositions of the products produced from stem wood, willow, forest residue and reed canary grass are in general terms rather similar, while the products obtained from bark differ to some extent. The oil produced from bark had a higher H/Ceff ratio and heating value which can be correlated to a higher amount of pyrolytic lignin and extractives when compared with oils produced from the other feedstocks. Regardless of the original feedstock, the composition of the different pyrolysis oil fractions (condensed and aerosol) differs significantly from each other. However this opens up the possibility to use specifically selected fractions in targeted applications. An increased reactor temperature generally results in a higher amount of water and water insoluble material, primarily as small lignin derived oligomers, in the produced oil.

  • 18. Jonsson, C.Y.C.
    et al.
    Stjernberg, J.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Lindblom, B.
    Bostrom, D.
    Ohman, M.
    Deposit formation in a grate-kiln plant for iron-ore pellet production.: Part 1: Characterization of process gas particles2013In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 10, p. 6159-6170Article in journal (Refereed)
    Abstract [en]

    Slag formation in the grate-kiln process is a major problem for iron-ore pellet producers. It is therefore important to understand the slag formation mechanism in the grate-kiln production plant. This study initiated the investigation by in situ sampling and identifying particles in the flue gas from a full-scale 40 MW grate-kiln production plant for iron-ore pelletizing. Particles were sampled from two cases of combustion with pulverized coal and heavy fuel oil. The sampling location was at the transfer chute that was situated between the traveling grate and the rotary kiln. The particle-sampling system was set up with a water-cooled particle probe equipped with nitrogen gas dilution, cyclone, and low-pressure impactor. Sub-micrometer and fine particles were size-segregated in the impactor, while coarse particles (>6 μm) were separated with a cyclone before the impactor. Characterization of these particles was carried out with environmental scanning electron microscopy (ESEM), and the morphology of sub-micrometer particles was studied with transmission electron microscopy (TEM). The results showed that particles in the flue gas consisted principally of fragments from iron-ore pellets and secondarily of ashes from pulverized coal and heavy fuel oil combustions. Three categories of particle modes were identified: (1) sub-micrometer mode, (2) first fragmentation mode, and (3) second fragmentation mode. The sub-micrometer mode consisted of vaporized and condensed species; relatively high concentrations of Na and K were observed for both combustion cases, with higher concentrations of Cl and S from heavy fuel oil combustion but higher concentrations of Si and Fe and minor P, Ca, and Al from coal combustion. The first fragmentation mode consisted of both iron-ore pellet fines and fly ash particles; a significant increment of Fe (>65 wt %) was observed, with higher concentrations of Ca and Si during heavy fuel oil combustion but higher concentrations of Si and Al during coal combustion. The second fragmentation mode consisted almost entirely of coarse iron-ore pellet fines, predominantly of Fe (∼90 wt %). The particles in the flue gas were dominantly iron-ore fines because the second fragmentation mode contributed >96 wt % of the total mass of collected particles. © 2013 American Chemical Society.

  • 19.
    Leijenhorst, Evert J.
    et al.
    BTG Biomass Technology Group BV, Netherlands.
    Assink, Daan
    BTG Biomass Technology Group BV, Netherlands.
    van de Beld, Bert
    BTG Biomass Technology Group BV, Netherlands.
    Weiland, Fredrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Carlsson, Per
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Öhrman, Olov G. W.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Entrained flow gasification of straw- and wood-derived pyrolysis oil in a pressurized oxygen blown gasifier2015In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 79, p. 166-176Article in journal (Refereed)
    Abstract [en]

    Fast pyrolysis oil can be used as a feedstock for syngas production. This approach can have certain advantages over direct biomass gasification. Pilot scale tests were performed to investigate the route from biomass via fast pyrolysis and entrained flow gasification to syngas. Wheat straw and clean pine wood were used as feedstocks; both were converted into homogeneous pyrolysis oils with very similar properties using in-situ water removal. These pyrolysis oils were subsequently gasified in a pressurized, oxygen blown entrained flow gasifier using a thermal load of 0.4 MW. At a pressure of 0.4 MPa and a lambda value of 0.4, temperatures around 1250 °C were obtained. Syngas volume fractions of 46% CO, 30% H2 and 23% CO2 were obtained for both pyrolysis oils. 2% of CH4 remained in the product gas, along with 0.1% of both C2H2 and C2H4. Minor quantities of H2S (3 vs. 23) cm3 m−3, COS (22 vs. 94) cm3 m−3 and benzene (310 vs. 532) cm3 m−3 were measured for wood- and straw derived pyrolysis oils respectively. A continuous 2-day gasification run with wood derived pyrolysis oil demonstrated full steady state operation. The experimental results show that pyrolysis oils from different biomass feedstocks can be processed in the same gasifier, and issues with ash composition and melting behaviour of the feedstocks are avoided by applying fast pyrolysis pre-treatment.

  • 20.
    Lestander, Torbjörn A.
    et al.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Sandström, Linda
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Öhrman, Olov
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Thyrel, Mikael
    SLU Swedish University of Agricultural Sciences, Sweden.
    Characterization of fast pyrolysis bio-oil properties by near-infrared spectroscopic data2018In: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250X, Vol. 133, p. 9-15Article in journal (Refereed)
    Abstract [en]

    Pyrolysis transforms bulky and heterogeneous lignocellulosic biomass into more easily-handled oils that can be upgraded into bio-based transportation fuels. Existing systems for monitoring pyrolysis processes and characterizing their products rely on slow and time-consuming wet chemical analyses. On-line near-infrared (NIR) spectroscopy could potentially replace such analyses, providing real-time data and reducing costs. To test the usefulness of NIR methods in characterizing pyrolysis oils and processes, biomass from conifers, Salix, and reed canary grass was milled and pyrolyzed at 675, 750, and 775 °C. Two separate pyrolytic fractions (aerosol and condensed) were produced in each experiment, and NIR spectra were collected for each fraction. Multivariate modelling of the resulting data clearly showed that the samples’ NIR spectra could be used to accurately predict important properties of the pyrolysis oils such as their energy values, main organic element (C, H and O) contents, and water content. The spectra also contained predictive information on the samples’ origins, fraction, and temperature treatment, demonstrating the potential of on-line NIR techniques for monitoring pyrolytic production processes and characterizing important properties of pyrolytic oils from lignocellulosic biomass.

  • 21.
    Molinder, Roger
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Sandström, Linda
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Characteristics of Particles in Pyrolysis Oil2016In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 30, no 11, p. 9456-9462Article in journal (Refereed)
    Abstract [en]

    Particles filtered out of pyrolysis oil produced through fast pyrolysis of stem wood, willow, reed canary grass, bark, and forest residue were characterized using scanning electron microscopy and energy-dispersive spectroscopy with the aim of identifying particle categories and discussing transport mechanisms of particles and inorganics into the oil. Particles filtered out of both the condensed and the aerosol fractions of the oil displayed three types of morphology: (i) char-like structures (1-15 μm), (ii) spheres (100 nm to 1 μm), and (iii) irregularly shaped residue (50-500 nm). The char-like structures were identified as char. The spheres and irregularly shaped residue shared morphology and composition with tar balls and organic particles with inorganic inclusions. These particles could have formed either during the fast pyrolysis stage or through precipitation from the oil during storage. All particles consisted mainly of C and O but also small amounts of inorganics. The particles from the aerosol fraction of the oil had higher inorganics content than the particles from the condensed fraction. The results were discussed, and suggested transport mechanisms of inorganics into particles were presented.

  • 22.
    Molinder, Roger
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Feeding small biomass particles at low rates2014In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 269, p. 240-246Article in journal (Refereed)
    Abstract [en]

    Biomass particles (75-1000μm) were fed at 9.0-66.5mgmin-1 (2.9-21.7W) using a particle feeder that dispensed particles by gravity through an injection tube. Feed rate was controlled by altering the velocity of a pusher block. Particles were agitated using a vibration motor and fed onto a balance and mass readings were continuously logged. Factors impacting reproducibility and feed rate stability were investigated as well as the effects of particle size and of pusher block velocity. Statistical analysis was applied to investigate patterns in particle feed rate data. Particle aggregation was identified as a factor which influenced feed rate stability and thereby also influencing reproducibility. Feed rate correlated well with pusher block velocity (R2=0.99). Statistical analysis showed strong indications (P values <0.01) of two patterns (clustering and trends) in the feed rate data which were attributed to changes in particle bed appearance with time. With all else being equal, particle size affected feed rate but not feed rate stability. A higher vibration amplitude was needed to agitate smaller particles. It was concluded that particle agitation control is a key to stable feeding of small biomass particles at low rates.

  • 23.
    Sandström, Linda
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Johansson, Ann-Christine
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Öhrman, Olov G. W.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Marklund, Magnus
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Pyrolysis of Nordic biomass types in a cyclone pilot plant — Mass balances and yields2016In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 152, p. 274-284Article in journal (Refereed)
    Abstract [en]

    Fast pyrolysis of biomass results in a renewable product usually denoted pyrolysis oil or bio-oil, which has been suggested to be used as a direct substitute for fuel oil or as a feedstock for production of transportation fuels and/or chemicals. In the present work, fast pyrolysis of stem wood (originated from pine and spruce), willow, reed canary grass, brown forest residue and bark has been performed in a pilot scale cyclone reactor. The experiments were based on a biomass feeding rate of 20 kg/h at three different reactor temperatures. At the reference condition, pyrolysis of stem wood, willow, reed canary grass, and forest residue resulted in organic liquid yields in the range of 41 to 45% w/w, while pyrolysis of bark resulted in lower organic liquid yields. Two fractions of pyrolysis oil were obtained, denoted as the condensed and the aerosol fraction. Most of the water soluble molecules were collected in the condensed fraction, whereas the yield of water insoluble, heavy lignin molecules was higher in the aerosol fraction. Based on the results of the present work, willow, reed canary grass and forest residue are considered as promising raw materials for production of pyrolysis oil in a cyclone reactor.

  • 24.
    Sefidari, H.
    et al.
    Luleå University of Technology, Sweden; LKAB, Sweden.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center. Luleå University of Technology, Sweden.
    Lindblom, B.
    Luleå University of Technology, Sweden; LKAB, Sweden.
    Nordin, L. O.
    LKAB, Sweden.
    Wu, G.
    GTT Technologies, Germany; Institute of Energy and Climate Research, Germany.
    Yazhenskikh, E.
    Institute of Energy and Climate Research, Germany.
    Müller, M.
    Institute of Energy and Climate Research, Germany.
    Ma, C.
    Umeå University, Sweden.
    Öhman, M.
    Luleå University of Technology, Sweden.
    Comparison of high-rank coals with respect to slagging/deposition tendency at the transfer-chute of iron-ore pelletizing grate-kiln plants: A pilot-scale experimental study accompanied by thermochemical equilibrium modeling and viscosity estimations2019In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 193, p. 244-262Article in journal (Refereed)
    Abstract [en]

    Iron-ore pelletizing plants use high-rank coals to supply the heat necessary to process ores. Ash material from coal, in combination with iron-ore dust originating from the disintegration of the pellets, can cause deposition/slagging which often leads to severe production losses and damage. Deposition/slagging is most prominent in the hot areas of the grate-kiln setup and is more severe at the inlet of the rotary-kiln, i.e., the transfer-chute. Following on from our previous work, high-rank bituminous coals with potential for use in the pelletizing process were combusted in a pilot-scale (0.4 MW) pulverized-coal fired experimental combustion furnace (ECF). The fly-ash particles and short-term deposits were characterized to shed light on the observed difference in slagging/deposition tendencies of the coals. Global thermodynamic equilibrium modeling, in combination with viscosity estimates, was used to interpret the experimental findings and investigate the effect of the coal-ash composition upon deposition/slagging. This approach was carried out with and without the presence of Fe2O3-rich pellet-dust under oxidizing conditions within the temperature range at the transfer-chute of iron-ore pelletizing rotary-kilns. Based on the findings, a Qualitative Slagging Indicator (QSI) was proposed that can help pre-screen new solid fuels for potential slagging issues. The proposed QSI highlights the following: (1) an inverse relationship between viscosity and slagging/deposition tendency of the coals was observed (2) as viscosity decreases (either with increasing temperature or due to the change in the coal-ash composition), stronger deposits will form that will complicate the mechanical removal of the deposited layer. It was therefore inferred that low viscosity molten phases facilitate deposition/slagging, which is exacerbated by the presence of fluxing agents (e.g., CaO, MgO, K2O, Na2O, and Fe2O3) in the deposits. The low viscosity coal-ash-induced molten phases are also more likely to interact with the Fe2O3-rich pellet-dust that results in further decreases in viscosity, thereby intensifying depositions. The results from this work complement the on-going research by our group to elucidate and alleviate ash-related problems in industrial grate kilns.

  • 25.
    Sefidari, Hamid
    et al.
    Luleå University of Technology, Sweden.
    Lindblom, Bo
    Luleå University of Technology, Sweden ; LKAB, Sweden.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center. Luleå University of Technology, Sweden.
    Nordin, Lars Olof
    LKAB, Sweden.
    Lennartsson, Andreas
    Luleå University of Technology, Sweden.
    Mouzon, Johanne
    Luleå University of Technology, Sweden.
    Bhuiyan, Iftehkar
    Luleå University of Technology, Sweden.
    Öhman, Marcus
    Luleå University of Technology, Sweden.
    The effect of disintegrated iron-ore pellet dust on deposit formation in a pilot-scale pulverized coal combustion furnace. Part II: Thermochemical equilibrium calculations and viscosity estimations2018In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 180, p. 189-206Article in journal (Refereed)
    Abstract [en]

    Fly ash particles from the combustion of solid-fuels together with disintegrated particles arising from iron-ore pellets result in accumulation of deposits on the refractory linings of the grate-kiln induration machine during the iron-ore pelletizing process. The deposits amass in the high-temperature regions of the induration furnace thus disturbing the flow of gas and pellets. Therefore, to tackle the above-mentioned issues, an understanding of deposit formation mechanism is of crucial importance. This study was conducted with the objective of addressing the effect of disintegrated iron-ore pellet dust on deposit formation and the mechanisms behind deposition (slagging) in the grate-kiln process. A comprehensive set of experiments was conducted in a 0.4 MW pilot-scale pulverized-coal- fired furnace where three different scenarios were considered as follows; Case 1 (reference case): Coal was combusted without the presence of pellet dust. Case 2: Natural gas was combusted together with simultaneous addition of pellet dust to the gas stream. Case 3: Coal was combusted together with the addition of pellet dust simulating the situation in the large-scale setup. Fly ash particles and short-term deposits were characterized and deposition was addressed in Part I of this study. In light of the experimental observations (Part I) and the thermochemical equilibrium calculations (Part II), a scheme of ash transformation during the iron-ore pelletizing process was proposed. The dissolution of hematite particles into the Ca-rich-aluminosilicate melt (from the coal-ash constituents) decreased the viscosity and resulted in the formation of stronger (heavily sintered) deposits. Overall, this pilot-scale work forms part of a wider study which aims at deepening the understanding of ash transformation phenomena during the large-scale pelletizing process.

  • 26.
    Sefidari, Hamid
    et al.
    Luleå University of Technology, Sweden.
    Lindblom, Bo
    Luleå University of Technology, Sweden.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center. Luleå University of Technology, Sweden.
    Nordin, Lars-Olof
    LKAB, Sweden.
    Mouzon, Johanna
    Luleå University of Technology, Sweden.
    Bhuiyan, Iftekhar Uddin
    Luleå University of Technology, Sweden.
    Öhman, Marcus
    Luleå University of Technology, Sweden.
    The effect of disintegrated iron-ore pellet dust on deposit formation in a pilot-scale pulverized coal combustion furnace. Part I: Characterization of process gas particles and deposits2018In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 177, p. 283-298Article in journal (Refereed)
    Abstract [en]

    To initiate the elucidation of deposit formation during the iron-ore pelletization process, a comprehensive set of experiments was conducted in a 0.4 MW pilot-scale pulverized-coal-fired furnace where three different scenarios were considered as follows; Case 1 (reference case): Coal was combusted without the presence of pellet dust. Case 2: Natural gas was combusted together with simultaneous addition of pellet dust to the gas stream. Case 3: Coal was combusted together with the addition of pellet dust simulating the situation in the large-scale grate-kiln setup. Particles and deposits were sampled from 3 positions of different temperature via a water-cooled sampling probe. Three distinct fragmentation modes were identified based on the aerodynamic particle diameter (Dp). The fine mode: Particles with 0.03 &lt; Dp &lt; 0.06 μm. The first fragmentation mode: Particles with 1 &lt; Dp &lt; 10 μm. The second fragmentation mode: Coarse particles (cyclone particles, Dp &gt; 10 μm). A transition from a bimodal PSD (particle size distribution) to a trimodal PSD was observed when pellet dust was added (Case 3) and consequently the elemental bulk composition of the abovementioned modes was changed. The most extensive interaction between pellet dust and coal-ash particles was observed in the coarse mode where a significant number of coal ash globules were found attached to the surface of the hematite particles. The morphology of the sharp-edged hematite particles was changed to smooth-edged round particles which proved that hematite particles must have interacted with the surrounding aluminosilicate glassy phase originating from the coal ash. The short-term deposits collected during coal combustion (Case 1) were highly porous in contrast to the high degree of sintering observed in the experiments with pellet dust addition (Case 3) which is attributed to the dissolution of hematite particles in the aluminosilicate glassy phase. The results suggest that pellet dust itself (Case 2) has low slagging tendency, independent of temperature. However, when coal-ash is present (Case 3), auxiliary phases are added such that tenacious particles are formed and slagging occurs.

  • 27.
    Sepman, Alexey
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Ögren, Yngve
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center. Luleå University of Technology, Sweden.
    Gullberg, Marcus
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center. Luleå University of Technology, Sweden.
    Development of TDLAS sensor for diagnostics of CO, H2O and soot concentrations in reactor core of pilot-scale gasifier2016In: Applied physics. B, Lasers and optics (Print), ISSN 0946-2171, E-ISSN 1432-0649, Vol. 122, no 2, p. 1-12, article id 29Article in journal (Refereed)
    Abstract [en]

    This paper reports on the development of the tunable diode laser absorption spectroscopy sensor near 4350 cm−1 (2298 nm) for measurements of CO and H2O mole fractions and soot volume fraction under gasification conditions. Due to careful selection of the molecular transitions [CO (υ″ = 0 → υ′ = 2) R34–R36 and H2O at 4349.337 cm−1], a very weak (negligible) sensitivity of the measured species mole fractions to the temperature distribution inside the high-temperature zone (1000 K < T < 1900 K) of the gasification process is achieved. The selected transitions are covered by the tuning range of single diode laser. The CO and H2O concentrations measured in flat flames generally agree better than 10 % with the results of 1-D flame simulations. Calibration-free absorption measurements of studied species in the reactor core of atmospheric pilot-scale entrained-flow gasifier operated at 0.1 MW power are reported. Soot concentration is determined from the measured broadband transmittance. The estimated uncertainties in the reactor core CO and H2O measurements are 15 and 20 %, respectively. The reactor core average path CO mole fractions are in quantitative agreement with the µGC CO concentrations sampled at the gasifier output.

  • 28.
    Sepman, Alexey
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Ögren, Yngve
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Qu, Zhechao
    Umeå University, Sweden.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Schmidt, Florian M.
    Umeå University, Sweden.
    Real-time in situ multi-parameter TDLAS sensing in the reactor core of an entrained-flow biomass gasifier2017In: Proceedings of the Combustion Institute, ISSN 1540-7489, E-ISSN 1873-2704, Vol. 36, no 3, p. 4541-4548Article in journal (Refereed)
    Abstract [en]

    Tunable diode laser absorption spectroscopy (TDLAS) was employed to measure several important process parameters at two different locations inside the reactor of an atmospheric air-blown 0.1 MW biomass gasifier. Direct TDLAS at 2298 nm was employed for CO and water calibration-free scanned wavelength modulation spectroscopy at 1398 nm for H2O and gas temperature and direct TDLAS at 770 nm for gaseous elemental potassium K(g) under optically thick conditions which correspond the first in situ measurements of K(g) and temperature in a reactor core and in biomass gasification respectively. Actual average temperatures in the reactor core were significantly higher than the uncorrected thermocouple measurements in the gas stream. The CO concentrations at the lower optical access port were comparable to those obtained by GC at the exhaust. In gasification mode similar H2O values were obtained by the two different TDLAS instruments. The reaction time was faster for peat than for stem wood.

  • 29.
    Sepman, Alexey
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Ögren, Yngve
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Optical techniques for characterizing the biomass particle flow fluctuations in lab- and pilot-scale thermochemical systems2017In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 313, p. 129-134Article in journal (Refereed)
    Abstract [en]

    The work demonstrates the performance of the optical extinction technique for real-time diagnostics of the fluctuations in biomass particle flows. The online measurements of fluctuations of density were used to determine the biomass particle mass flow fluctuations. Biomass flows were produced using laboratory biomass particle feeder (mass flux up to 10 g/min) and the hopper-screw feeding system of the pilot-scale entrained flow rector, mass flux up to 500 g/min, located at SP ETC in Piteå. The experiments showed that the time-averaged extinction appeared to be linearly related to the real particle mass flow. The relatively fast variations in biomass feeding rates measured using the extinction technique were confirmed by fast balance measurements (in laboratory feeder experiments) and by real-time tunable diode laser CO and H2O concentrations measured in the reactor core of the entrained flow gasifier.

  • 30.
    Simonsson, Johan
    et al.
    Lund University, Sweden.
    Bladh, Henrik
    Lund University, Sweden.
    Gullberg, Marcus
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Pettersson, Esbjörn
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Sepman, Alexey
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Ögren, Yngve
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Bengtsson, Per-Erik
    Lund University, Sweden.
    Soot Concentrations in an Atmospheric Entrained Flow Gasifier with Variations in Fuel and Burner Configuration Studied Using Diode-Laser Extinction Measurements2016In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 30, no 3, p. 2174-2186Article in journal (Refereed)
    Abstract [en]

    Soot concentration measurements were performed using diode-laser extinction in an atmospheric air-blown entrained flow gasifier at two vertical levels. The gasifier was operated at different air-fuel equivalence ratios and with variations in fuel and burner configurations. Two fuels were investigated: wood powder and peat powder. These were burned using two burner configurations, one giving a rotating flow inside the gasifier (swirl), and one where the fuel and air were injected parallel with the gasifier axis (jet). The diode-laser measurements were performed at the wavelength 808 nm from which the soot concentrations were estimated, and additionally at 450 nm in order to gain insight into the spectral dependence of the extinction to estimate measurement quality. Additional diagnostic techniques were used, such as an electrical low-pressure impactor (ELPI) for soot size distributions and gas chromatography for species concentration measurements. The results show that wood powder produces higher soot concentrations than peat powder, especially at lower air-fuel equivalence ratios. Furthermore, the burner configuration had in general much less impact than the choice of fuel on the soot concentration.

  • 31. Stjernberg, J.
    et al.
    Jonsson, C.Y.C.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Lindblom, B.
    Bostrom, D.
    Ohman, M.
    Deposit formation in a grate-kiln plant for iron-ore pellet production.: Part 2: Characterization of deposits2013In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 10, p. 6171-6184Article in journal (Refereed)
    Abstract [en]

    Buildup of deposit material in chunks on refractory linings caused by combustion of various fuels is a well-known problem. This study characterizes the short-term deposits on refractory material in a grate-kiln process, carried out through in situ measurements using a water-cooled probe with a part of a refractory brick mounted in its end. Sampling was carried out during combustion of both oil and coal. A significant difference in deposition rates was observed; deposition during oil firing was negligible compared to coal firing. The deposits are mainly hematite particles embedded in bonding phase, mainly comprising Si, Al, Fe, Ca, and O. Moreover, it was found that the prevailing flue-gas direction determines the formation of the deposits on the probe and that inertial impaction controls the deposition rate. However, this rate can also be affected by the amount of air-borne particles present in the kiln. © 2013 American Chemical Society.

  • 32.
    Strandberg, Anna
    et al.
    Umeå University, Sweden.
    Holmgren, Per
    Umeå University, Sweden.
    Wagner, David R.
    Umeå University, Sweden.
    Molinder, Roger
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Umeki, Kentaro
    Luleå University of Technology, Sweden.
    Broström, Markus
    Umeå University, Sweden.
    Effects of Pyrolysis Conditions and Ash Formation on Gasification Rates of Biomass Char2017In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 31, no 6, p. 6507-6514Article in journal (Refereed)
    Abstract [en]

    Pyrolysis conditions and the presence of ash-forming elements significantly influence char properties and its oxidation or gasification reactivity. In this study, intrinsic gasification rates of char from high heating rate pyrolysis were analyzed with isothermal thermogravimetry. The char particles were prepared from two biomasses at three size ranges and at two temperatures. Reactivity dependence on original particle size was found only for small wood particles that had higher intrinsic char gasification rates. Pyrolysis temperature had no significant effect on char reactivity within the range tested. Observations of ash formation highlighted that reactivity was influenced by the presence of ash-forming elements, not only at the active char sites but also through prohibition of contact between char and gasification agent by ash layer formation with properties highly depending on ash composition.

  • 33.
    Toth, Pal
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Brackmann, Christian
    Lund University, Sweden.
    Ögren, Yngve
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Mannazhi, Manu
    Lund University, Sweden.
    Simonsson, Johan
    Lund University, Sweden.
    Sepman, Alexey
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Bengtsson, Per Erik
    Lund University, Sweden.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Experimental and numerical study of biomass fast pyrolysis oil spray combustion: Advanced laser diagnostics and emission spectrometry2019In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 252, p. 125-134Article in journal (Refereed)
    Abstract [en]

    The objective of this work was to move towards developing a comprehensible Computational Fluid Dynamics (CFD) model to facilitate the predictive modeling of Fast Pyrolysis Oil (FPO) spray combustion. A CFD model was implemented from the literature and results were compared to 2D data from non-intrusive optical diagnostics involving Planar Laser Induced Fluorescence of the OH radical, Mie scattering imaging and two-color pyrometry using a laboratory-scale, CH 4 /air flat-flame with an air-assist atomizer. Furthermore, flame radiation and contributions from graybody sources, chemiluminescence and soot were studied experimentally using emission spectroscopy and Laser Induced Incandescence (LII). Reasonable qualitative agreement was found between experimental and model results in terms of flame structure and temperature. Emission spectroscopy and LII results revealed and confirmed earlier observations regarding the low soot concentration of FPO spray flames; furthermore, it was shown that a significant portion of flame radiation originated from graybody char radiation and chemiluminescence from the Na-content of the FPO. These suggest that the treatment of soot formation might not be important in future computational models; however, the description of char formation and Na chemiluminescence will be important for accurately predicting temperature and radiation profiles, important from the point of e.g., large-scale power applications. Confirmed low soot concentrations are promising from an environmental point of view.

  • 34.
    Toth, Pal
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center. University of Miskolc, Hungary.
    Jacobsson, Daniel
    Lund University, Sweden.
    Ek, Martin
    Lund University, Sweden.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center. Luleå University of Technology, Sweden.
    Real-time, in situ, atomic scale observation of soot oxidation2019In: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 145, p. 149-160Article in journal (Refereed)
    Abstract [en]

    The oxidation of soot is a complex process due to the heterogeneous structure of the material. Several mechanisms have been hypothesized based on ex situ studies, but need confirmation from in situ observation; furthermore, deeper insight is needed to develop and validate structure-dependent reaction mechanisms. In this work, soot oxidation was for the first time observed at atomic scale in situ, in real-time, using a spherical aberration-corrected Environmental Transmission Electron Microscope. The transformation of individual soot particles was followed through from initiation to complete conversion. Observations clearly showed the existence of different burning modes and particle fragmentation previously hypothesized in the literature. Furthermore, transitioning between the modes—affected by temperature and O2 pressure—was unambiguously observed, explaining previous observations regarding structure-dependent and time-varying oxidation rates. A new mode of burning in which oxidation happens rapidly in the bulk phase with the disruption of long-range lamellar order was observed and is suspected to be dominant at practically relevant conditions. The ability to unambiguously relate different burning modes in terms of nanostructure will be of importance for optimizing both soot emission abatement and properties of nanoparticulate carbon products.

  • 35.
    Toth, Pal
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center. University of Miskolc, Hungary.
    Vikström, Therese
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Molinder, Roger
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Structure of carbon black continuously produced from biomass pyrolysis oil2018In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 20, no 17, p. 3981-3992Article in journal (Refereed)
    Abstract [en]

    Renewable-based carbon black was produced using pyrolysis oil derived from pine and spruce stem wood as feedstock in a continuous, high-temperature spray process. The particle size, micro- and nanostructure of the carbon black particles were investigated using High Resolution Transmission Electron Microscopy. The effect of process parameters on the structural properties of the product was studied. Conditions that yielded products structurally similar to commercial carbon black were identified. The results indicate that biomass pyrolysis oil can be used as a feedstock to produce renewable-based carbon black in a continuous process that is flexible and scalable. The structural properties of the products depended on process temperature and were consistent with those of commercial carbon black.

  • 36.
    Toth, Pal
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center. University of Miskolc, Hungary.
    Ögren, Yngve
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Sepman, Alexey
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Vikström, Therese
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Gren, Per
    Luleå University of Technology, Sweden.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Spray combustion of biomass fast pyrolysis oil: Experiments and modeling2019In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 237, p. 580-591Article in journal (Refereed)
    Abstract [en]

    In this work, we are the first to report a detailed comparison between the predictions of a current Computational Fluid Dynamics (CFD) model for describing Fast Pyrolysis Oil (FPO) spray combustion and results from a laboratory-scale experiment. The objectives were to assess the predictive power of the CFD model, evaluate its usefulness in a numerical optimization scenario and characterize the spray flame. The spray flame was produced by using an air-assist atomizer piloted by a CH4/air flat-flame. Pyrolysis oil from a cyclone fast pyrolysis plant was combusted. The flame was characterized by using two-color pyrometry, Tunable Diode Laser Absorption Spectroscopy and high-magnification shadowgraphy. Overall, the assessed model correctly predicted flame structure and seemed appropriate for engineering applications, but lacked predictive power in estimating droplet size distributions. Numerical results were the most sensitive to variations in the initial droplet size distribution; however, seemed robust to changes in the multicomponent fuel formulation. Several conclusions were drawn regarding FPO spray combustion itself; e.g., the amount of produced soot in the flames was very low and droplets exhibited microexplosion behavior in a characteristic size-shape regime. 

  • 37.
    Weiland, Fredrik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Hedman, Henry
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Marklund, Magnus
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Öhrman, Olov .G.W
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Gebart, Rikard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Pressurized oxygen blown entrained-flow gasification of wood powder2013In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 2, p. 932-941Article in journal (Refereed)
    Abstract [en]

    In the present study, an oxygen blown pilot scale pressurized entrained-flow biomass gasification plant (PEBG, 1 MWth) was designed, constructed, and operated. This Article provides a detailed description of the pilot plant and results from gasification experiments with stem wood biomass made from pine and spruce. The focus was to evaluate the performance of the gasifier with respect to syngas quality and mass and energy balance. The gasifier was operated at an elevated pressure of 2 bar(a) and at an oxygen equivalence ratio (λ) between 0.43 and 0.50. The resulting process temperatures in the hot part of the gasifier were in the range of 1100-1300 °C during the experiments. As expected, a higher λ results in a higher process temperature. The syngas concentrations (dry and N 2 free) during the experiments were 25-28 mol % for H2, 47-49 mol % for CO, 20-24 mol % for CO2, and 1-2 mol % for CH 4. The dry syngas N2 content was varied between 18 and 25 mol % depending on the operating conditions of the gasifier. The syngas H 2/CO ratio was 0.54-0.57. The gasifier cold gas efficiency (CGE) was approximately 70% for the experimental campaigns performed in this study. The synthesis gas produced by the PEBG has potential for further upgrading to renewable products, for example, chemicals or biofuels, because the performance of the gasifier is close to that of other relevant gasifiers. © 2013 American Chemical Society.

  • 38.
    Weiland, Fredrik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Hedman, Henry
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center. Luleå University of Technology, Sweden.
    Marklund, Magnus
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Pressurized entrained flow gasification of pulverized biomass - Experiences from pilot scale operation2016In: Chemical Engineering Transactions, ISSN 1974-9791, E-ISSN 2283-9216, Vol. 50, p. 325-330Article in journal (Refereed)
    Abstract [en]

    One of the goals in the national energy strategy of Sweden is that the vehicle fleet should be independent of fossil fuels by 2030. To reach that goal and to domestically secure for supply of alternative fuels, one of the suggested routes is methanol production from forest residues via pressurized and oxygen blown entrained flow gasification. In this context, ongoing industrial research in a 1 MWth gasification pilot plant is carried out at SP Energy Technology Center (SP ETC) in Pitea, Sweden. The plant is operated with pulverized or liquid fuels at process pressures up to 10 bar and this work summarizes the experiences from over 600 hours of operation with forest based biomass fuels. This paper covers results from thorough process characterization as well as results from extractive samplings of both permanent gases and particulate matter (soot) from inside the hot gasifier. Furthermore, the challenges with pressurized entrained flow gasification of pulverized biomass are discussed. During the characterization work, four of the most important process parameters (i.e. oxygen stoichiometric ratio (λ), fuel load, process pressure and fuel particle size distribution) were varied with the purpose of studying the effect on the process performance and the resulting syngas quality. The experimental results showed that the maximum cold gas efficiency (CGE) based on all combustible species in the syngas was 75% (at λ=0.30), whereas the corresponding value based only on CO and H2 (with respect to further MeOH synthesis from the syngas) was 70% (at λ=0.35). As expected, the pilot experiments showed that both the soot yield and soot particle size was reduced by increasing λ. One of the additional conclusions from this work was that; minimizing heat losses from the gasifier is of utmost importance to optimize the process performance regarding energy efficiency (i.e. CGE). Therefore, a well-insulated refractory lined gasifier is the primary alternative in regards to reactor design to maximize the CGE. Future development of the PEBG process should focus on identifying suitable hot-phase refractory, that exhibit long life-time and can sustain the alkali-rich biomass ash under gasification conditions. In addition to this, the remaining issue around how to improve the slag flow from the reactor, by additives or fuel mixing, should be investigated.

  • 39.
    Weiland, Fredrik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Nilsson, P.T.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Gebart, Rikard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Gudmundsson, A.
    Sanati, M.
    Online characterization of syngas particulates using aerosol mass spectrometry in entrained-flow biomass gasification2014In: Aerosol Science and Technology, ISSN 0278-6826, E-ISSN 1521-7388, Vol. 48, no 11, p. 1145-1155Article in journal (Refereed)
    Abstract [en]

    Entrained flow gasification is a promising technique where biomass is converted to a synthesis gas (syngas) under fuel-rich conditions. In contrast to combustion, where the fuel is converted to heat, CO2, and H2O, the syngas from gasification is rich in energetic gases such as CO and H2. These compounds (CO and H2) represent the building blocks for further catalytic synthesis to chemicals or biofuels. Impurities in the syngas, such as particulates, need to be reduced to different levels depending on the syngas application. The objective of this work was to evaluate the amount of particulates; the particle size distribution and the particle composition from entrained flow gasification of pine stem wood at different operating conditions of the gasifier. For this purpose, online time resolved measurements were performed with a soot particle aerosol mass spectrometer (SP-AMS) and a scanning mobility particle sizer (SMPS). The main advantage of SP-AMS compared to other techniques is that the particle composition (soot, PAH, organics, and ash forming elements) can be obtained with high time resolution and thus studied as a direct effect of the gasifier-operating conditions. The results suggest that syngas particulates were essentially composed of soot at these tested process temperatures in the reactor (1200-1400°C). Furthermore, the AMS analysis showed a clear correlation between the amounts of polycyclic aromatic hydrocarbons (PAH) and soot in the raw syngas. Minimization of soot and PAH yields from entrained flow gasification of wood proved to be possible by further increasing the O2 addition.

  • 40.
    Weiland, Fredrik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Nordwaeger, M.
    Olofsson, I.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Nordin, Anders
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Entrained flow gasification of torrefied wood residues2014In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 125, p. 51-58Article in journal (Refereed)
    Abstract [en]

    In this work, four different fuels were gasified in a pressurized entrained flow pilot plant gasifier at approximately 270 kWth. The different fuels were; two torrefied wood residues, one raw wood residue and one torrefied stem wood. The system pressure and oxygen equivalence ratio (λ) were held constant for all four gasification experiments. It was found that the torrefaction pretreatment significantly reduced the milling energy consumption for fuel size reduction, which in turn contributed to increased gasification plant efficiency. Furthermore, the results indicate that the carbon conversion efficiency may be enhanced by an intermediate torrefaction pretreatment, whereas both less severe torrefaction and more severe torrefaction resulted in reduced carbon conversions. The results also indicate that the CH4 yield was significantly reduced for the most severely torrefied fuel. © 2014 Elsevier B.V. All rights reserved.

  • 41.
    Weiland, Fredrik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Sweeney, Daniel J.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center. Luleå University of Technology, Sweden.
    Extractive Sampling of Gas and Particulates from the Reactor Core of an Entrained Flow Biomass Gasifier2016In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 30, no 8, p. 6405-6412Article in journal (Refereed)
    Abstract [en]

    With the purpose of demonstrating a process for pressurized entrained flow gasification for pulverized biomass, the aim with this work was to characterize the conditions inside the gasifier. To gain a broader understanding, it was important to extract both gases and particulate matter from the hot reaction zone. The objectives were, therefore, to (1) develop a sampling system capable of extracting both gas and particulates from the gasifier, (2) study the production of particulate matter as well as its composition and size distribution as a function of different operating conditions, and (3) extract time-resolved data for the syngas species (CO, CO2, and CH4) in order to study the compositional variance. The results indicated that the syngas heating value was lower at the sampling position in the gasifier compared to the heating value measured downstream of the quench cooler. The difference was most probably an effect of ongoing gasification of carboneous solids downstream of the sampling position in the gasifier. Furthermore, it was concluded that the fuel feedrate was fluctuating, most likely because of heterogeneity in the fuel powder and/or the challenges in the fuel feeding system itself. With regards to particulate matter in the syngas, it was shown to mostly consist of soot. The soot yield was significantly reduced by increasing γ. The reactor core sampling system proved superior to the traditional sampling system downstream of the quench with regard to measuring soot yield at different operating conditions of the gasifier. Finally, it was concluded that the submicron fly ash particles from oxygen blown biomass gasification contain high propotions of refractory elements (e.g., Ca, Mg, and Si) in addition to the more volatile elements (e.g., K, Na, S, and Cl). This is probably due to extremely high temperature in the flame and substoichiometric condition in the gasifier, which may promote vaporization of refractory elements during char gasification.

  • 42.
    Weiland, Fredrik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Hedman, H.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Marklund, Magnus
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Gebart, Rikard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Pressurized entrained flow gasification of biomass powder: Initial results from pilot plant experiments2012In: The 4th Nordic Wood Biorefinery Conference, 2012Conference paper (Refereed)
  • 43.
    Wiinikka, Henrik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Carlsson, Per
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Granberg, F.
    Löfström, J.
    Marklund, Magnus
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Tegman, R.
    Lindblom, M.
    Gebart, Rikard
    Design and methodology of a high temperature gas sampling system for pressurized black liquor gasification.2010In: Fuel, Vol. 89, p. 2583-2591Article in journal (Refereed)
  • 44.
    Wiinikka, Henrik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Carlsson, Per
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Marklund, Magnus
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Grönberg, C
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Pettersson, Esbjörn
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Lidman, M
    Gebart, Rikard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Experimental investigation of an industrial scale black liquor gasifier: Part 2: Influence of quench operation on product gas composition2012In: Fuel, Vol. 93, p. 117-129Article in journal (Refereed)
  • 45.
    Wiinikka, Henrik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Gebart, Rikard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Critical parameters for particle emissions in small-scale fixed-bed combustion of wood pellets2004In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 18, no 4, p. 897-907Article in journal (Refereed)
    Abstract [en]

    In this study, laboratory experiments in a small-scale (10 kW) reactor have been performed to investigate the particle formation mechanisms and the influence of different operating parameters on the particle emissions from combustion of wood pellets under fixed-bed conditions. The results presented herein show that the particles from fixed-bed combustion are formed from three different mechanisms: coarse fly ash particles (> 10 μm) are released by mechanical ejection from the fuel bed, submicrometer-sized fly ash particles are produced from the vaporization and nucleation of ash minerals, and, finally, submicrometer-sized soot particles are produced from incomplete combustion. Significant effects on the particle emissions have been observed for the combustor wall temperature and the flow pattern in the combustion zone. Increasing the combustor wall temperature yields a decrease in the emissions of coarse fly ash and soot particles; however, the emissions of submicrometer-sized fly ash particles increase simultaneously. For example, the emissions of soot are reduced by a factor of ∼5 and the emissions of fly ash are increased by a factor of ∼2 when the wall temperature increases from 400 °C to 950 °C. Increasing the mixing rate in the combustion chamber will also decrease the emissions of soot particles. An important conclusion from this study is that the total emissions of particles can be minimized in fixed-bed combustion of a solid biomass by minimizing the combustion temperature in the burning char particle and maximizing the temperature in the secondary combustion zone. © 2004 American Chemical Society.

  • 46.
    Wiinikka, Henrik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Gebart, Rikard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Experimental investigations of the influence from different operating conditions on the particle emissions from a small-scale pellets combustor2004In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 27, no 6, p. 645-652Article in journal (Refereed)
    Abstract [en]

    The purpose of this study is to determine how different design parameters in an idealised small-scale combustor affect the emission of particulates in the flue gas and to provide insight that can be used for design optimisation. The design parameters are the primary air factor, the total air factor and the magnitude of swirling flow in the combustion chamber. Particles from the reactor were collected from two different sampling lines, one located in the combustion zone, just above the fuel bed, and the other in the flue stack after the reactor. The measurements show that this burner gives very low emissions of particulates and CO in the flue gas. Furthermore, the concentration of particles in the flue gas is uncoupled to the concentration of particles immediately above the fuel bed, probably as a result of a well-designed secondary air supply. The variable that had the strongest effect on the total particulate emission from the combustor was the total air factor. In order to understand the qualitative differences in the flow nature between different operating conditions, CFD simulations of the flow field were also performed. © 2004 Elsevier Ltd. All rights reserved.

  • 47.
    Wiinikka, Henrik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Gebart, Rikard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    The influence of air distribution rate on particle emissions in fixed bed combustion of biomass2005In: Combustion Science and Technology, ISSN 0010-2202, E-ISSN 1563-521X, Vol. 177, no 9, p. 1747-1766Article in journal (Refereed)
    Abstract [en]

    Combustion of biomass under fixed-bed conditions will generate both coarse and fine particles that have a negative effect on technical performance or pose health hazards. It is therefore important to reduce the emissions of these particles that are already in the combustion process. The aim of this study was to experimentally investigate how different air supply strategies affect the particle emission in fixed-bed combustion of biomass. The air was supplied either through the grate, through a secondary air register, or equally divided between the two. The results showed that the air supply affects the emissions of both coarse and especially fine fly ash particles. The emissions of fine particles decrease when the air supply through the grate decreases, probably due to lower oxygen concentration in the fuel bed and thereby lower temperature in the burning char particles, which results in less vaporisation of ash elements. Hence, changing or optimizing the air supply strategy appears to be an attractive way to reduce the particle emissions already in the combustion process. Copyright © Taylor & Francis Inc.

  • 48.
    Wiinikka, Henrik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Gebart, Rikard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    The influence of fuel type on particle emissions in combustion of biomass pellets2005In: Combustion Science and Technology, ISSN 0010-2202, E-ISSN 1563-521X, Vol. 177, no 4, p. 741-763Article in journal (Refereed)
    Abstract [en]

    Three different biomass fuels (bark pellets, wood pellets and granulates made from hydrolysis residues) were burned under identical conditions to determine the effect of biomass type on the amount and composition of the combustion-generated particles under fixed-bed conditions. Significant differences in emissions of dust, submicron particles, and the shape of the particle number and mass size distributions were found between the different biomass fuels. For the particles that were dominated by ash elements, the particle emissions were correlated to the ash concentration in the unburned fuel. However, if the combustion condition allowed for organic particles, the "sooting" tendency of the fuel was found to become more important than the amount of ash in the fuel. Furthermore, the fuel type affects the particle emissions more than changes in reactor operating parameters. Copyright © Taylor & Francis Inc.

  • 49.
    Wiinikka, Henrik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Gebart, Rikard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Boman, Christoffer
    Bostrom, D.
    Nordin, Anders
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Ohman, M.
    High-temperature aerosol formation in wood pellets flames: Spatially resolved measurements2006In: Combustion and Flame, ISSN 0010-2180, E-ISSN 1556-2921, Vol. 147, no 4, p. 278-293Article in journal (Refereed)
    Abstract [en]

    The formation and evolution of high-temperature aerosols during fixed bed combustion of wood pellets in a realistic combustion environment were investigated through spatially resolved experiments. The purpose of this work was to investigate the various stages of aerosol formation from the hot flame zone to the flue gas channel. The investigation is important both for elucidation of the formation mechanisms and as a basis for development and validation of particle formation models that can be used for design optimization. Experiments were conducted in an 8-kW-updraft fired-wood-pellets combustor. Particle samples were withdrawn from the centerline of the combustor through 10 sampling ports by a rapid dilution sampling probe. The corresponding temperatures at the sampling positions were in the range 200-1450 °C. The particle sample was size-segregated in a low-pressure impactor, allowing physical and chemical resolution of the fine particles. The chemical composition of the particles was investigated by SEM/EDS and XRD analysis. Furthermore, the experimental results were compared to theoretical models for aerosol formation processes. The experimental data show that the particle size distribution has two peaks, both of which are below an aerodynamic diameter of 2.5 μm (PM2.5). The mode diameters of the fine and coarse modes in the PM2.5 region were ∼0.1 and ∼ 0.8   μm, respectively. The shape of the particle size distribution function continuously changes with position in the reactor due to several mechanisms. Early, in the flame zone, both the fine mode and the coarse mode in the PM2.5 region were dominated by particles from incomplete combustion, indicated by a significant amount of carbon in the particles. The particle concentrations of both the fine and the coarse mode decrease rapidly in the hot oxygen-rich flame due to oxidation of the carbon-rich particles. After the hot flame, the fine mode concentration and particle diameter increase gradually when the temperature of the flue gas drops. The main contribution to this comes from condensation on preexisting particles in the gas of alkali sulfates, alkali chlorides, and Zn species formed from constituents vaporized in the fuel bed. The alkali sulfates were found to condense at a temperature of ∼ 950 ° C and alkali chlorides condensed later at ∼ 600 ° C. This agrees well with results of chemical equilibrium calculation of the gas-to-particle conversion temperature. After the hot flame the coarse mode concentration decreased very little when the flue gas was cooled. In addition to carbon, the coarse mode consists of refractory metals and also considerable amounts of alkali. © 2006 The Combustion Institute.

  • 50.
    Wiinikka, Henrik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Gebart, Rikard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Boman, Christoffer
    Bostrom, D.
    Ohman, M.
    Influence of fuel ash composition on high temperature aerosol formation in fixed bed combustion of woody biomass pellets2007In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 86, p. 181-193Article in journal (Refereed)
    Abstract [en]

    In this work, the influence of fuel ash composition on high temperature aerosol formation during fixed bed combustion of woody biomass (two wood pellets and one bark pellets) were investigated experimentally in a laboratory reactor and theoretically through chemical equilibrium model calculations. For all fuels, the particle mass size distribution in the PM2.5 region was bimodal, with one fine mode and one coarse mode. Early in the flame, the fine mode was dominated by particles from incomplete combustion and these particles were rapidly oxidised in the post flame zone. After the hot flame, the fine mode concentration and the particle diameter increases gradually when the temperature decreases due to condensation of vaporised inorganic matter, K, Na, S, Cl, and Zn. For two of the fuels also P could be found in the fine particles. The coarse mode consisted of carbon, refractory metals and considerable amount of alkali. Further, the initial fuel alkali concentration and the alkali to silicon ratio (K + Na)/Si influenced the amount of vaporised aerosol forming alkali matter. Finally, the present study shows that, combustion temperature and fuel ash composition is of major importance for the formation of high temperature aerosols in fixed bed combustion of woody biomass pellets. © 2006 Elsevier Ltd. All rights reserved.

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