Change search
Refine search result
1 - 39 of 39
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the 'Create feeds' function.
  • 1.
    Arrhenius, Karine
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Organisk kemi (Kmo).
    Yaghooby, Haleh
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Kemi.
    Smajovic, Nijaz
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Kemi.
    Optimization of an analytical method for the measurement of oil carryover from a compressor in compressed natural gas refueling stations2015In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 29, no 4, p. 2416-2421Article in journal (Refereed)
  • 2.
    Atongka Tchoffor, Placid
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi, Förbrännings- och aerosolteknik.
    Davidsson, Kent
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi, Förbrännings- och aerosolteknik.
    Thunman, Henrik
    Effects of Steam on the Release of Potassium, Chlorine, and Sulfur during Char Conversion, Investigated under Dual Fluidized Bed Gasification Conditions2014In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 28, no 11, p. 6953-6965Article in journal (Refereed)
  • 3.
    Atongka Tchoffor, Placid
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi, Förbrännings- och aerosolteknik.
    Davidsson, Kent
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi, Förbrännings- och aerosolteknik.
    Thunman, Henrik
    Transformation and Release of Potassium, Chlorine, and Sulfur from Wheat Straw under Conditions Relevant to Dual Fluidized Bed Gasification2013In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 12, p. 7510-7520Article in journal (Refereed)
  • 4. Boman, Christoffer
    et al.
    Pettersson, E.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Westerholm, R.
    Bostrom, D.
    Nordin, Anders
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Stove performance and emission characteristics in residential wood log and pellet combustion: Part 1: Pellet stoves2011In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 25, no 1, p. 307-314Article in journal (Refereed)
    Abstract [en]

    Stove performance, characteristics, and quantities of gaseous and particulate emissions were determined for two different pellet stoves, varying fuel load, pellet diameter, and chimney draft. This approach aimed at covering variations in emissions from stoves in use today. The extensive measurement campaign included CO, NOx, organic gaseous carbon, volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), total particulate matter (PMtot) as well as particle mass and number concentrations, size distributions, and inorganic composition. At high load, most emissions were similar. For stove B, operating at high residual oxygen and solely with primary air, the emissions of PMtot and particle numbers were higher while the particles were smaller. Lowering the fuel load, the emissions of CO and hydrocarbons increased dramatically for stove A, which operated continuously also at lower fuel loads. On the other hand for stove B, which had intermittent operation at lower fuel loads, the emissions of hydrocarbons increased only slightly lowering the fuel load, while CO emissions increased sharply, due to high emissions at the end of the combustion cycle. Beside methane, dominating VOCs were ethene, acetylene, and benzene and the emissions of VOC varied in the range 1.1-42 mg/MJfuel. PAH emissions (2-340 μg/MJfuel) were generally dominated by phenanthrene, fluoranthene and pyrene. The PM tot values (15-45 mg/MJfuel) were in all cases dominated by fine particles with mass median diameters in the range 100-200 nm, peak mobility diameters of 50-85 nm, and number concentrations in the range 4 × 1013 to 3 × 1014 particles/MJfuel. During high load conditions, the particulate matter was totally dominated by inorganic particles at 15-25 mg/MJfuel consisting of potassium, sodium, sulfur, and chlorine, in the form of K2SO4, K 3Na(SO4)2, and KCl. The study shows that differences in operation and modulation principles for the tested pellet stoves, relevant for appliances in use today, will affect the performance and emissions significantly, although with lower scattering in the present study compared to compiled literature data. © 2011 American Chemical Society.

  • 5. Brus, E.
    et al.
    Ohman, M.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Nordin, Anders
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Bostrom, D.
    Hedman, Henry
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Eklund, A.
    Bed agglomeration characteristics of biomass fuels using blast-furnace slag as bed material2004In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 18, no 4, p. 1187-1193Article in journal (Refereed)
    Abstract [en]

    Agglomeration of bed material may cause severe operating problems during fluidized bed combustion. The attack or coating layers that are formed on the bed particles during combustion play an important role in the agglomeration process. To reduce bed agglomeration tendencies, alternative bed materials may be used. In this paper, bed agglomeration characteristics during the combustion of biomass fuels using a relatively new bed material (iron blast-furnace slag) as well as ordinary quartz sand were determined. Controlled agglomeration tests lasting 40 h, using five representative biomass fuels (bark, olive residue, peat, straw, and reed canary grass) were conducted in a bench-scale fluidized bed. The bed materials and agglomerates were analyzed using SEM/EDS and X-ray diffraction. Chemical equilibrium calculations were performed to interpret the experimental findings. The results showed that blast-furnace slag had a lower tendency to agglomerate than quartz sand for most of the fuels. The quartz particles showed an inner attack layer more often than did the blast-furnace slag. The blast-furnace slag had a lower tendency to react with elements from the fuel. The outer coating layer had similar characteristics and thickness for both bed materials when the same fuel was combusted. However, the inner attack layer thickness was larger for quartz particles. SEM/EDS analyses of the agglomerates showed that the inner Ca-K-silicate-rich attack layer was responsible for the agglomeration of quartz sand. The composition of blast-furnace slag agglomerate was similar to the outer coating layer. Chemical equilibrium calculations showed that the original composition of the blast-furnace slag was close to the equilibrium composition, and hence there was no major driving force for reactions between that bed material and K and Ca from the fuel. The homogeneous silica-rich attack layer (with a low melting temperature) was not formed to the same extent for blast-furnace slag, thus explaining the lower bed agglomeration tendency. © 2004 American Chemical Society.

  • 6.
    Carlsson, Per
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Iisa, K
    Gebart, Rikard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Computational fluid dynamics simulations of raw gas composition from a black liquor Gasifier: Comparison with experiments2011In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 25, no 9, p. 4122-4128Article in journal (Refereed)
    Abstract [en]

    Pressurized entrained flow high temperature black liquor gasification can be used as a complement or a substitute to the Tomlinson boiler used in the chemical recovery process at kraft pulp mills. The technology has been proven on the development scale, but there are still no full scale plants. This work is intended to aid in the development by providing computational tools that can be used in scale up of the existing technology. In this work, an existing computational fluid dynamics (CFD) model describing the gasification reactor is refined. First, one-dimensional (1D) plug flow reactor calculations with a comprehensive reaction mechanism are performed to judge the validity of the global homogeneous reaction mechanism used in the CFD simulations in the temperature range considered. On the basis of the results from the comparison, an extinction temperature modification of the steam-methane reforming reaction was introduced in the CFD model. An extinction temperature of 1400 K was determined to give the best overall agreement between the two models. Next, the results from simulations of the flow in a 3 MW pilot gasifier with the updated CFD model are compared to experimental results in which pressure, oxygen to black liquor equivalence ratio, and residence time have been varied. The results show that the updated CFD model can predict the main gas components (H 2, CO, CO2) within an absolute error of 2.5 mol %. CH 4 can be predicted within an absolute error of 1 mol %, and most of the trends when process conditions are varied are captured by the model. © 2011 American Chemical Society.

  • 7.
    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.

  • 8.
    Elliott, Douglas C.
    et al.
    Pacific Northwest National Laboratory, US.
    Meier, Dietrich
    Thünen Institute of Wood Research, Germany.
    Oasmaa, Anja
    VTT Technical Research Center of Finland, Finland.
    Van De Beld, Bert
    BTG Biomass Technology Group BV, Netherlands.
    Bridgwater, Anthony V.
    Aston University, UK.
    Marklund, Magnus
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Results of the International Energy Agency Round Robin on Fast Pyrolysis Bio-oil Production2017In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 31, no 5, p. 5111-5119Article in journal (Refereed)
    Abstract [en]

    An international round robin study of the production of fast pyrolysis bio-oil was undertaken. A total of 15 institutions in six countries contributed. Three biomass samples were distributed to the laboratories for processing in fast pyrolysis reactors. Samples of the bio-oil produced were transported to a central analytical laboratory for analysis. The round robin was focused on validating the pyrolysis community understanding of production of fast pyrolysis bio-oil by providing a common feedstock for bio-oil preparation. The round robin included: distribution of three feedstock samples, hybrid poplar, wheat straw, and a blend of lignocellulosic biomasses, from a common source to each participating laboratory, preparation of fast pyrolysis bio-oil in each laboratory with the three feedstocks provided, and return of the three bio-oil products (minimum of 500 mL) with operational description to a central analytical laboratory for bio-oil property determination. The analyses of interest were CHN, S, trace element analysis, water, ash, solids, pyrolytic lignin, density, viscosity, carboxylic acid number, and accelerated aging of bio-oil. In addition, an effort was made to compare the bio-oil components to the products of analytical pyrolysis through gas chromatography/mass spectrometry (GC/MS) analysis. The results showed that clear differences can occur in fast pyrolysis bio-oil properties by applying different process configurations and reactor designs in small scale. The comparison to the analytical pyrolysis method suggested that pyrolysis (Py)-GC/MS could serve as a rapid qualitative screening method for bio-oil composition when produced in small-scale fluid-bed reactors. Gel permeation chromatography was also applied to determine molecular weight information. Furthermore, hot vapor filtration generally resulted in the most favorable bio-oil product, with respect to water, solids, viscosity, and carboxylic acid number. These results can be helpful in understanding the variation in bio-oil production methods and their effects on bio-oil product composition.

  • 9. Eriksson, G.
    et al.
    Hedman, Henry
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Bostrom, D.
    Pettersson, E.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Backman, Rainier
    Ohman, M.
    Combustion characterization of rapeseed meal and possible combustion applications2009In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 23, no 8, p. 3990-3939Article in journal (Refereed)
    Abstract [en]

    A future shortage of biomass fuel can be foreseen. The production of rapeseed oil for a number of purposesis increasing, among others, for biodiesel production. A yproduct from the oil extraction process is rapeseed meal (RM), presently used as animal feed. Further increases in supply will make fuel use an option. Several energy companies have shown interest but have been cautious because of the scarcity of data on fuel properties, which led to the present study. Combustion-relevant properties of RM from several producers have been determined. The volatile fraction (74 ± .06%wt ds) is comparable to wood; the moisture content (6.2-11.8%wt) is low; and the ash content (7.41 ± 0.286%wt ds) is high compared to most other biomass fuels. The lower heating value is 18.2 ± 0.3 MJ/kg (dry basis). In comparison to other biomass fuels, the chlorine content is low (0.02-0.05%wt ds) and the sulfur content is high (0.67-0.74%wt ds). RM has high contents of nitrogen (5.0-6.4%wt ds), phosphorus (1.12-1.23%wt ds), and potassium (1.2-1.4%wt ds). Fuel-specific combustion properties of typical RM were determined through combustion tests, with an emphasis on gas emissions, ash formation, and potential ash-related operational problems. Softwood bark was chosen as a suitable and representative co-combustion (woody) fuel. RM was added to the bark at two levels: 10 and 30%wt ds. These mixtures were pelletized, and so was RM without bark (for durability mixed with cutter shavings, contributing 1%wt of the ash). Each of these fuels was combusted in a 5 kWfluidized bed and an underfed pellet burner (to simulate grate combustion). Pure RM was combusted in a powder burner. Emissions of NO and SO2 were high for all combustion tests, requiring applications with flue gas cleaning, economically viable only at large scale. Emissions of HCl were relatively low. Temperatures for initial bed agglomeration in the fluidized-bed tests were high for RM compared to many other agricultural fuels, thereby indicating that RM could be an attractive fuel from a bed agglomeration point of view. The results of grate combustion suggest that slagging is not likely to be severe for RM, pure or mixed with other fuels. Fine-mode particles from fluidized-bed combustion and grate combustion mainly contained sulfates of potassium, suggesting that the risk of problems caused by deposit formation should be moderate. The chlorine concentration of the particles was reduced when RM was added to bark, potentially lowering the risk of high-temperature corrosion. Particle emissions from powder combustion of RM were 17 times higher than for wood powder, and the fine-mode fraction contained mainly K-phosphates known to cause deposits, suggesting that powder combustion of RM should be used with caution. A possible use of RM is as a sulfur-containing additive to biomass fuels rich in Cl and K for avoiding ash-related operational problems in fluidized beds and grate combustors originated from high KCl concentrations in the flue gases © 2009 American Chemical Society.

  • 10.
    Gall, Dan
    et al.
    University of Gothenburg, Sweden.
    Pushp, Mohit
    RISE - Research Institutes of Sweden, Safety and Transport, Safety.
    Davidsson, Kent O.
    RISE - Research Institutes of Sweden, Built Environment, Energy and Circular Economy.
    Pettersson, Jan B. C.
    University of Gothenburg, Sweden.
    Online Measurements of Alkali and Heavy Tar Components in Biomass Gasification2017In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 31, no 8, p. 8152-8161Article in journal (Refereed)
    Abstract [en]

    Tar and alkali metal compounds are released during biomass gasification and have a major impact on the operation and performance of gasification processes. Herein we describe a novel method for characterization of alkali and heavy tar compounds in the hot product gas formed during gasification. Gas is continuously extracted, cooled and diluted, which results in condensation of tar and alkali into aerosol particles. The thermal stability of these particles is subsequently evaluated using a volatility tandem differential mobility analyzer (VTDMA) method. The technique is adopted from aerosol science where it is frequently used to characterize the thermal properties of aerosol particles. Laboratory studies show that pure and mixed alkali salts and organic compounds evaporate in well-defined temperature ranges, which can be used to determine the chemical composition of particles. The performance of the VTDMA is demonstrated at a 4 MWth dual fluidized bed gasifier using two different types of online sampling systems. Alkali metal compounds and a wide distribution of heavy tar components with boiling points above 400°C are observed in the product gas. Implications and potential further improvements of the technique are discussed.

  • 11.
    Gall, Dan
    et al.
    University of Gothenburg, Sweden.
    Pushp, Mohit
    RISE - Research Institutes of Sweden, Safety and Transport, Safety.
    Larsson, Anton
    Göteborg Energi AB, Sweden.
    Davidsson, Kent
    RISE - Research Institutes of Sweden, Built Environment, Energy and Circular Economy.
    Pettersson, Jan B. C.
    University of Gothenburg, Sweden .
    Online Measurements of Alkali Metals during Start-up and Operation of an Industrial-Scale Biomass Gasification Plant2018In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 32, no 1, p. 532-541Article in journal (Refereed)
    Abstract [en]

    Alkali metal compounds may have positive influences on biomass gasification by affecting char reactivity and tar reforming but may also disturb the process by formation of deposits and agglomerates. We herein present results from online measurements of alkali compounds and particle concentrations in a dual fluidized bed gasifier with an input of 32 MWth. A surface ionization detector was used to measure alkali concentrations in the product gas, and aerosol particle measurement techniques were employed to study concentrations and properties of condensable components in the gas. Measurements were performed during start-up and steady-state operation of the gasifier. The alkali concentration increased to approximately 200 mg m-3 when fuel was fed to the gasifier and continued to rise during activation of the olivine bed by addition of potassium carbonate, while the alkali concentration was in the range from 20 to 60 mg m-3 during steady-state operation. Addition of fresh bed material and recirculated ash had noticeable effects on the observed alkali concentrations, and K2CO3 additions to improve tar chemistry resulted in increased levels of alkali in the product gas. Addition of elemental sulfur led to reduced concentrations of CH4 and heavy tars, while no clear influence on the alkali concentration was observed. The study shows that alkali concentrations are high in the product gas, which has implications for the fluidized bed process, tar chemistry, and operation of downstream components including coolers, filters, and catalytically active materials used for product gas reforming.

  • 12.
    Jones, Frida
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi, Förbrännings- och aerosolteknik.
    Tran, Honghi
    Lindberg, Daniel K
    Zhao, Liming
    Hupa, Mikko
    Thermal Stability of Zinc Compounds2013In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 10, p. 5663-5669Article in journal (Refereed)
  • 13. 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.

  • 14. Kaombe, D.K.
    et al.
    Lenes, M.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Toven, K.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Glomm, W.R.
    Turbiscan as a tool for studying the phase separation tendency of pyrolysis oil2013In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27Article in journal (Refereed)
  • 15. Lindstrom, E.
    et al.
    Sandstrom, M.
    Bostrom, D.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Ohman, M.
    Slagging characteristics during combustion of cereal grains rich in phosphorus2007In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 21, no 2, p. 710-717Article in journal (Refereed)
    Abstract [en]

    A residential cereal burner (20 kW) was used study the slagging characteristics of cereal grains with and without lime addition. The deposited bottom ash and slag were analyzed using X-ray diffraction (XRD), to identify the crystalline phases, and environmental scanning electron microscopy, coupled with energy-dispersive X-ray spectroscopy (ESEM/EDS), to study the morphology and elemental composition. Phase-diagram information was utilized to extract qualitative information about the behavior of cereal grain ashes under combustion conditions. Chemical equilibrium model calculations were used to interpret the experimental results. In addition, investigations of the melting behavior of the produced slags were conducted. The results showed significant differences in slagging characteristics between the fuels that were used. The slags consisted of high-temperature melting crystalline phases (calcium/magnesium potassium phosphates) and a potassium-rich phosphate melt for all cereal grains. For oat and barley, cristobalite was also identified in the slag. Furthermore, in these cases, the slags most probably contained a potassium-rich silica melt. The differences in the melting behaviors of the slags had a considerable effect on the performance of the burner. The addition of lime reduced the formation of slag for barley and totally eliminated it for rye and wheat. This occurs because lime contributes to the formation of high-temperature melting calcium potassium phosphates. © 2007 American Chemical Society.

  • 16. Ma, C.
    et al.
    Weiland, Fredrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Hedman, Henry
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Bostrom, D.
    Backman, Rainier
    Ohman, M.
    Characterization of reactor ash deposits from pilot-scale pressurized entrained-flow gasification of woody biomass2013In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 11, p. 6801-6814Article in journal (Refereed)
    Abstract [en]

    Pressurized entrained-flow gasification of renewable forest residues has the potential to produce high-quality syngas suitable for the synthesis of transport fuels and chemicals. The ash transformation behavior during gasification is critical to the overall production process and necessitates a level of understanding to implement appropriate control measures. Toward this end, ash deposits were collected from inside the reactor of a pilot-scale O 2-blown pressurized entrained-flow gasifier firing stem wood, bark, and pulp mill debarking residue (PMDR) in separate campaigns. These deposits were characterized with environmental scanning electron microscopy equipped with energy-dispersive X-ray spectrometry and X-ray diffractometry. The stem wood deposit contained high levels of calcium and was comparatively insubstantial. The bark and PMDR fuels contained contaminant sand and feldspar particles that were subsequently evident in each respective deposit. The bark deposit consisted of lightly sintered ash aggregates comprising presumably a silicate melt that enveloped particles of quartz and, to a lesser degree, feldspars. Discontinuous layers likely to be composed of alkaline-earth metal silicates were found upon the aggregate peripheries. The PMDR deposit consisted of a continuous slag that contained quartz and feldspar particles dispersed within a silicate melt. Significant levels of alkaline-earth and alkali metals constituted the silicate melts of both the bark and PMDR deposits. Overall, the results suggest that fuel contaminants (i.e., quartz and feldspars) play a significant role in the slag formation process during pressurized entrained-flow gasification of these woody biomasses. © 2013 American Chemical Society.

  • 17.
    Molinder, R.
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Sandström, L.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wiinikka, H.
    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. © 2016 American Chemical Society.

  • 18.
    Niklasson, Fredrik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi, Förbrännings- och aerosolteknik.
    Jones, Frida
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi, Förbrännings- och aerosolteknik.
    Effects of reduced bed temperature in laboratory-and full-scale fluidized-bed boilers: Particle, deposit, and ash chemistry2013In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 8, p. 4999-5007Article in journal (Refereed)
  • 19.
    Ohman, M.
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Boman, Christoffer
    Hedman, Henry
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Eklund, R.
    Residential combustion performance of pelletized hydrolysis residue from lignocellulosic ethanol production2006In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 20, no 3, p. 1298-1304Article in journal (Refereed)
    Abstract [en]

    As a result of the production of ethanol from lignocellulosic material by acid hydrolysis, a large quantity of non-hydrolyzed material is obtained as a residue, mainly derived from the lignin in the wood. One possible economical use of this hydrolysis residue is as raw material for production of fuel pellets to be used in residential pellet appliances (i.e., stoves and burners). The combustion characteristics of single pellets, as well as combustion results (i.e., ash deposition, maintenance, and emission performance) in residential pellet appliances, were therefore determined for hydrolysis residue pellets and compared with corresponding results using wood pellets. The hydrolysis residue pellets had a lower slagging tendency, as well as a higher heating value and lower ash content, than the wood (stem) pellets. During combustion in residential pellet appliances, relatively similar gaseous emission performance and characteristics were obtained for hydrolysis residue and stem wood pellets. However, the results showed a significant potential for very low emissions of fine particles during combustion of hydrolysis residue pellets because of the low content of volatile inorganic constituents. Tendencies for char-aggregate formation at low temperature (<800 °C) were identified during combustion of hydrolysis residue pellets. A practical implementation of the results in this work, both regarding accessibility and emission performance, is therefore to recommend the use of continuous-feed equipment thereby preserving a high temperature during the whole operation time. Thus, the results show that pelletized hydrolysis residue from lignocellulosic ethanol production could be a very interesting material for future residential pellet appliances designed for this typical biomass fuel. © 2006 American Chemical Society.

  • 20.
    Ohman, M.
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Bostrom, D.
    Nordin, Anders
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Hedman, Henry
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Effect of kaolin and limestone addition on slag formation during combustion of wood fuels2004In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 18, no 5, p. 1370-1376Article in journal (Refereed)
    Abstract [en]

    Ash-related problems have more than occasionally been observed in wood-fuel-fired boilers and also recently in wood-pellet burners. These problems can lead to reduced accessibility of the combustion systems as well as bad publicity for the market. The objectives of the present work were, therefore, to determine the effects of kaolin and limestone addition on the slagging propensities of problematic and problem-free wood fuels during combustion in residential pellet appliances (burners), thus contributing to the understanding of the role of kaolin and limestone in preventing slagging on furnace grates. Pellets with additive-to-fuel ratios between 0 and 0.7 wt %d.s. were combusted in three different types of burner constructions (10 kW): over-, horizontal-, and under-feeding of the fuel. The collected slag deposits from the under-fed burner as well as the corresponding deposited fly ash in the boiler were characterized with X-ray diffraction (XRD) and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The initial sintering temperatures of the formed slags were also determined. By adding limestone with an additive-to-fuel ratio of 0.5 wt %d.s. to the problematic stemwood raw material (Si-enriched probably because of contamination of sand/soil), the severe slagging of the fuel could totally be eliminated. Adding kaolin to the problematic raw material gave a minor decrease in slagging tendency of the problematic raw material and a major increase in slagging tendency of the problem-free stemwood raw material. When adding limestone to the problematic raw material, the composition of the formed slag was changed from relatively low temperature melting silicates to high temperature melting silicates and oxides. On the other hand, kaolin addition to the problematic raw material changed the content of the slag from mainly Ca-Mg silicates to be dominated by K-Al silicates which have relatively low melting points. When introducing kaolin to the problem-free raw material, the high temperature melting Ca-Mg oxides react to form lower temperature melting Ca-Al-K silicates. Chemical equilibrium model calculations were used to interpret the experimental findings, and generally good qualitative agreements between modeling and experimental results were obtained. © 2004 American Chemical Society.

  • 21.
    Ohman, M.
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Nordin, Anders
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    A new method for quantification of fluidized bed agglomeration tendencies: A sensitivity analysis1998In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 12, no 1, p. 90-94Article in journal (Refereed)
    Abstract [en]

    A new method for quantification of fluidized bed agglomeration tendencies for different fuels has been developed and evaluated. A bench scale fluidized bed reactor (5 kW), specially designed to obtain a homogeneous isothermal bed temperature, is used. The method is based on controlled increase of the bed temperature by applying external heat to the primary air and to the bed section walls. In addition, temperature homogeneity is secured by switching from normal fuel feeding to a propane precombustor. The initial agglomeration temperature is determined by on-or off-line principal component analysis of the variations in measured bed temperatures (four values) and differential pressures (four). To determine potential effects of all the process related variables, an extensive sensitivity analysis was performed. Experiments were performed according to a statistical experimental design to evaluate the effects of eight different process analytical variables on the determined agglomeration temperature of a biomass fuel. The results showed that for a given fuel, the amount of bed material, heating rate, fluidization velocity, and air to fuel ratio during both "ashing" and heating did not influence the determined agglomeration temperature. Only ash to bed material ratio, the ashing temperature, and the bed material particle size had significant effects on the agglomeration temperature, but still the effects were relatively small. The agglomeration temperature of the fuel could be determined to 899 °C (avg) with a reproducibility of ±5 °C (SD). The inaccuracy was determined to be ±30 °C (SD). Based on the results, the method was standardized with respect to ash to bed material ratio, bed material particle size, and ashing temperature. Relative agglomeration temperatures of different fuels, fuel, and additive combinations can thus be determined with a high precision.

  • 22.
    Ohman, M.
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Nordin, Anders
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    The role of kaolin in prevention of bed agglomeration during fluidized bed combustion of biomass fuels2000In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 14, no 3, p. 618-624Article in journal (Refereed)
    Abstract [en]

    Agglomeration of bed material and fuel ash may cause problems during fluidized bed combustion of biomass fuels. Previous results have shown that a "sticky" coating, which covered the original bed material and consisted of Ca-K-silicates, was directly responsible for the bed agglomeration during biomass combustion. The melting behavior (stickiness) of these coatings was very sensitive to the potassium content. Prior studies have also indicated that bed agglomeration could possibly be prevented by introducing low-cost additives such as kaolinite. The objectives of the present work were, therefore, to illustrate the effect of kaolin addition on the actual agglomeration temperature of two troublesome biomass fuels, and to contribute to the understanding of the role of kaolin in prevention of bed agglomeration. By controlled agglomeration experiments in a 5 kW bench scale fluidized bed reactor, the critical temperatures for agglomeration in a normal quartz bed when firing wheat straw or bark were determined to be 739 and 988°C, respectively. By adding kaolin, 10% w/w of the total amount of the bed, the initial bed agglomeration temperatures increased to 886 and 1000°C, respectively. Samples of bed materials, collected throughout the experimental runs, as well as final agglomerates were analyzed using SEM/EDS and X-ray diffraction. These results showed that kaolin was transformed to meta-kaolinite particles, which adsorbed potassium species. The increased agglomeration temperature was explained by the decreased fraction of melt in the bed particle coatings, i.e., coatings were somewhat depleted in the potassium content by the corresponding potassium-enrichment in the kaolin-derived aggregates.

  • 23.
    Ohman, M.
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Nordin, Anders
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Lundholm, K.
    Bostrom, D.
    Hedman, Henry
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Lundberg, M.
    Ash transformations during combustion of meat-, bonemeal, and RDF in a (bench-scale) fluidized bed combustor2003In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 17, no 5, p. 1153-1159Article in journal (Refereed)
    Abstract [en]

    Following the recent Bovine spongiform encephalopathy (BSE) experiences, thermal treatment of meat- and bonemeal (MBM) in existing fluidized bed combustion (FBC) plants for refuse-derived fuels (RDFs) has evolved as an interesting disposal and disintegration method. However, only a limited number of studies have previously been performed for combustion of MBM in fluidized beds. The objectives of the present work were, therefore, to determine the bed agglomeration tendencies of these materials during combustion in fluidized beds and to evaluate the effects of dolomite and kaolin addition to the fuel mix, as well as to elucidate the overall ash transformation mechanisms governing the potential bed agglomeration and fouling processes. By controlled agglomeration experiments in a 5 kW bench-scale fluidized bed reactor, the fuel-specific critical agglomeration temperatures in normal quartz bed material were determined for the different fuel/additive mixtures. All collected samples of bed materials, final bed agglomerates, and cyclone ashes were analyzed using SEM/EDS and XRD. The results indicated that the MBM fuels could be expected to be problematic concerning bed agglomeration in normal quartz beds, while kaolin and possibly dolomite addition could be used to reduce this risk to moderate levels. A significant elemental fractionation between the bed material and the cyclone ash was obtained. Apatite (Ca5(PO4)3(OH) or potentially some other calcium phosphates are elutriated from the bed and enriched in the fly ash, while sodium and potassium are enriched in the bed material. The characteristics and the corresponding melting behavior estimations of the necks formed between agglomerated bed particles suggest that silicate melts are responsible for the bed agglomeration. Results from XRD analysis of the fly ash formed from the fuels used in the present study indicated that the risk for melt-related fly ash problems seem relatively small.

  • 24.
    Ohman, M.
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Nordin, Anders
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Skrifvars, B.-J.
    Backman, Rainier
    Hupa, M.
    Bed agglomeration characteristics during fluidized bed combustion of biomass fuels2000In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 14, no 1, p. 169-178Article in journal (Refereed)
    Abstract [en]

    The in-bed behavior of ash-forming elements in fluidized bed combustion (FBC) of different biomass fuels was examined by SEM/EDS analysis of samples collected during controlled agglomeration test runs. Eight fuels were chosen for the test. To cover the variations in biomass characteristics and to represent as many combinations of ash-forming elements in biomass fuels as possible, the selection was based on a principal-component analysis of some 300 biomass fuels, with respect to ash-forming elements. The fuels were then combusted in a bench-scale fluidized bed reactor (5 kW), and their specific agglomeration temperatures were determined. Bed samples were collected throughout the tests, and coatings and necks formed were characterized by SEM/EDS analyses. On the basis of their compositions, the corresponding melting behaviors were determined, using data extracted from phase diagrams. The bench-scale reactor bed samples were finally compared with bed samples collected from biomass-fired full-scale fluidized bed boilers. In all the analyzed samples, the bed particles were coated with a relatively homogeneous ash layer. The compositions of these coatings were most commonly constricted to the ternary system K2O-CaO-SiO2. Sulfur and chlorine were further found not to `participate' in the agglomeration mechanism. The estimated melting behavior of the bed coating generally correlated well with the measured agglomeration temperature, determined in the 5 kW bench-scale fluidized bed reactor. Thus, the results indicate that partial melting of the coating of the bed particles would be directly responsible for the agglomeration.

  • 25. Olwa, Joseph
    et al.
    Öhman, Marcus
    Pettersson, Esbjörn
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Boström, Dan
    Okure, Mackay
    Kjellström, Björn
    Potassium retention in updraft gasification of wood2013In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 11, p. 6718-6724Article in journal (Refereed)
    Abstract [en]

    The release of compounds of K with producer gas during biomass gasification is known to play significant roles in fouling and high-temperature corrosion in boilers and high-temperature heat exchangers as well as blades in gas turbines that use producer gas as fuel. These phenomena are a major setback in the application of biomass fuel in combination with advanced process conditions. Updraft gasification provides gas filtering by the fuel bed with a gas cooling effect, conditions anticipated to create an avenue for K retention in the gasifier. The objective of this study was to determine the K retention potential of such gasifiers during wood gasification. Samples for the determination of the fate of K compounds included in the feedstock were collected from the generated producer gas using Teflon filters and gas wash bottles and also from wall deposits and ash residues. Analyses of samples were carried out using inductively coupled plasma-atomic emission spectrometry/mass spectrometry and X-ray diffraction methods. The finding was that about 99% of K was retained in the gasifier. K was found in the ash samples as a crystalline phase of K 2Ca(CO3)2(s) (fairchildite). A possible reaction mechanism leading to the formation of K2Ca(CO 3)2 is discussed in the paper. The 1% K understood as released, equivalent to 1200 ppbw content of K entrained in the producer gas stream, exceeds a known limit for application of the gas in conventional gas turbines. This would suggest application of the gas in an externally fired gas turbine system, where some limited K and other depositions in the heat exchanger can be relatively easy to handle. © 2013 American Chemical Society.

  • 26.
    Pettersson, E.
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Boman, Christoffer
    Westerholm, R.
    Bostrom, D.
    Nordin, Anders
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Stove performance and emission characteristics in residential wood log and pellet combustion: Part 2: Wood stove2011In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 25, no 1, p. 315-323Article in journal (Refereed)
    Abstract [en]

    The characteristics and quantities of a large number of gaseous and particulate emission components during combustion in a residential wood log stove with variations in fuel, appliance and operational conditions were determined experimentally. The measurement campaign included CO, NOx, organic gaseous carbon (OGC), volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), total particulate matter (PMtot) as well as particle mass and number concentrations, size distributions, and inorganic composition. CO varied in the range of 1100 to 7200 mg/MJ fuel, while OGC varied from 210 to 3300 mg/MJfuel. Dominating VOCs were methane, followed by ethene, acetylene, and benzene. Methane varied from 9 to 1600 mg/MJfuel. The nonmethane volatile organic compound (NMVOC) emissions were in the range of 20-2300 mg/MJ fuel. The PAHtot emissions varied from 1.3 to 220 mg/MJfuel, in most cases dominated by phenantrene, fluoranthene, and pyrene. PMtot were in all cases dominated by fine particles and varied in the range 38-350 mg/MJfuel. The mass median particle diameters and the peak mobility diameters of the fine particles varied in the range 200-320 and 220-330 nm, respectively, and number concentrations in the range of 1-4 × 1013 particles/MJfuel. Air starved conditions, at high firing intensity, gave the highest emissions, especially for hydrocarbons. This type of condition is seldom considered, though it may occur occasionally. The emissions from Swedish wood stoves, comparing a Swedish field study, are covered fairly well with the applied methodology, but other field studies report considerably higher emissions especially for diluted particle sampling. © 2011 American Chemical Society.

  • 27.
    Pettersson, E.
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Lindmark, F.
    Ohman, M.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Nordin, Anders
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Westerholm, R.
    Boman, Christoffer
    Design changes in a fixed-bed pellet combustion device: Effects of temperature and residence time on emission performance2010In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 24, no 2, p. 1333-1340Article in journal (Refereed)
    Abstract [en]

    The use of wood fuel pellets has proven to be well-suited for the small-scale market, enabling controlled and efficient combustion with low emission of products of incomplete combustion (PIC). Still, a potential for further emission reduction exists, and a thorough understanding of the influence of combustion conditions on the emission characteristics of air pollutants, such as polycyclic aromatic hydrocarbons (PAHs) and particulatematter (PM), is important. The objective of the present work was to determine the effect of design changes, i.e., increasing the temperature and/or residence time, on the emission performance and characteristics for a pellet combustion device using a laboratory fixed-bed reactor (<5 kW). The temperature and residence time after the bed sectionwere varied according to statistical experimental designs (650-950 °C and 0.5-3.0 s) with the emission responses: CO, organic gaseous carbon (OGC), NO, volatile organic compounds (VOCs, 20 compounds), PAHs (43 compounds), PMtot mass concentration, fine particle mass/count median diameter (MMD and CMD), and number concentration. The temperature was negatively correlated with the emissions of all studied PIC, with limited effects of the residence time. The PMtot emissions of 15-20 mg/MJwere in all cases dominated by fine (<1 μm) particles of K,Na, S, Cl,C,O, and Zn. An increased residence time resulted in increased fine particle sizes (i.e., MMD and CMD) and decreased number concentrations. The importance of a high temperature (>850 °C) in the bed zone with intensive, air-rich, and well-mixed conditions was illustrated forwood pellets combustion with almost a total depletion of all studied PIC. The importance of the residence time was shown to be limited, and the results emphasize the need for further verification studies and technology development work. Copyrigh © 2010 American Chemical Society.

  • 28.
    Simonsson, J
    et al.
    Combustion Physics, Lund University.
    Bladh, H
    Combustion Physics, Lund University.
    Gullberg, M
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Pettersson, E
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Sepman, A
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Ögren, Y
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wiinikka, H
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Bengtsson, P.E.
    Combustion Physics, Lund University.
    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. © 2016 American Chemical Society.

  • 29.
    Sophonrat, Nanta
    et al.
    KTH Royal Institute of Technology, Sweden.
    Sandström, Linda
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Johansson, Ann-Christine
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Yang, Weihong
    KTH Royal Institute of Technology, Sweden.
    Co-pyrolysis of Mixed Plastics and Cellulose: An Interaction Study by Py-GC×GC/MS2017In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 31, no 10, p. 11078-11090Article in journal (Refereed)
    Abstract [en]

    Understanding of the interaction between cellulose and various plastics is crucial for designing waste-to-energy processes. In this work, co-pyrolysis of polystyrene (PS) and cellulose was performed in a Py-GC×GC/MS system at 450-600 °C with ratios 70:30, 50:50, and 30:70. Polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET) were then added to the mixture with different ratios. It was found that co-pyrolysis of PS and cellulose promotes the formation of aromatic products with a large increase in the yield of ethylbenzene as compared to the calculated value from individual feedstock. This indicates interactions between cellulose and PS pyrolysis products. Observations from experiments including more than one type of plastics indicate that the interactions between different plastics are more pronounced than the interaction between plastics and cellulose.

  • 30. 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.

  • 31.
    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.

  • 32.
    Szamosi, Zoltan
    et al.
    University of Miskolc, Hungary.
    Toth, Pal
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Koos, Tamas
    University of Miskolc, Hungary.
    Baranyai, Viktor Zsolt
    Bay Zoltán Nonprofit Limited for Applied Research, Hungary.
    Szepesi, Gabor L.
    University of Miskolc, Hungary.
    Simenfalvi, Zoltan
    University of Miskolc, Hungary.
    Explosion Characteristics of Torrefied Wheat Straw, Rape Straw, and Vine Shoots Fuels2017In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 31, no 11, p. 12192-12199Article in journal (Refereed)
    Abstract [en]

    Torrefaction is a method for upgrading raw biomass to produce solid fuels that exhibit higher energy density relative to that of the raw material. In countries that produce significant amounts of agricultural residues, torrefaction may facilitate the utilization of waste in the energy sector by adding value to the raw fuel and opening pathways for new applications. In typical scenarios for utilization as fuel, both the raw and torrefied materials are stored in granular form. Dependent upon the properties of the granular material, the risk of dust explosion may be significant. Torrefaction changes the physical and chemical properties of the biomass and, therefore, affect explosion risk and severity. This work investigates the dust explosion characteristics of raw and torrefied agricultural wastes typically produced in Central European countries. The objective is to provide a characterization of these fuels in terms of explosion properties and make recommendations on storage design and safety. Three residues were studied: wheat straw, rape straw, and vine shoots. The samples were characterized in terms of their particle size, proximate and ultimate compositions, calorific properties, thermogravimetric behavior, and standard explosion characteristics. Torrefaction increased the explosivity of all three residues. Of the three samples, wheat straw was the least explosive, which is explained by the lowest amount of open cellular pores generated during torrefaction. Scanning electron microscopy imaging and thermogravimetry results suggested that the amount of open pores is the most significant contributor to the increase of explosivity caused by torrefaction, as opposed to increasing brittleness and fragmentation. For plants switching from using raw residues to torrefied fuels, the required area of typical explosion panels increases by 18-21% in the case of wheat and rape straw and by 26-30% in the case of vine shoots.

  • 33. Teghammar, A.
    et al.
    Castillo, Maria del Pilar 
    RISE, SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Ascue, Johnny
    RISE, SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Niklasson, C.
    Sarvari-Horvath, I.
    Improved anaerobic digestion by the addition of paper tube residuals: Pretreatment, stabilizing, and synergetic effects2013In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 1, p. 277-284Article in journal (Refereed)
    Abstract [en]

    This study deals with the addition of paper tube residuals to a nitrogen-rich mixture of organic waste obtained from industrial and municipal activities. This nitrogen-rich mixture, called buffer tank substrate (BTS) in the following text, is used in a large-scale biogas plant. The effects were investigated in semi-continuous co-digestion processes, and variations in operational conditions were studied. The addition of paper tubes had stabilizing effects, prevented the failure of the process, and made it possible to decrease the hydraulic retention time from 25 to 20 days. Furthermore, synergetic effects were found, with 15-34% higher methane yields, when paper tubes were co-digested with BTS. Moreover, steam explosion pretreatment of the paper tube waste with the addition of 0-2% NaOH was evaluated by batch digestion experiments. Increasing the NaOH concentrations used in the pretreatment resulted in increasing methane yields, with the highest of 403 N mL of CH 4 g-1 of volatile solids (VS) corresponding to an increase by 50% compared to that when untreated paper was digested (268 N mL of CH 4 g-1 of VS). The long-term effects of this best pretreatment were further investigated by continuous co-digestion experiments, leading to a higher methane yield when pretreated paper tubes were used in the co-digestion process compared to untreated. © 2012 American Chemical Society.

  • 34.
    Weiland, F.
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Sweeney, D. J.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wiinikka, H.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    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. © 2016 American Chemical Society.

  • 35.
    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.

  • 36.
    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.

  • 37.
    Wiinikka, Henrik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Gronberg, C.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Boman, Christoffer
    Emissions of heavy metals during fixed-bed combustion of six biomass fuels2013In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 2, p. 1073-1080Article in journal (Refereed)
    Abstract [en]

    Few studies examine heavy metal emissions during the small-scale combustion of various solid biofuels. This issue may become more important, as one can expect new regulations governing such emissions from biomass combustion similar to those governing waste incineration. This paper investigates the emissions of particulate-associated heavy metals (i.e., Sb, As, Cd, Co, Cr, Cu, Pb, Mn, Ni, Tl, V, Hg, and Zn) during the fixed-bed combustion of six solid biofuels (i.e., stemwood from birch and pine/spruce, bark from birch and pine, salix, and oat grains) and of peat and bituminous coal for comparison. The results indicate that the flue gas concentration (normalized to 11% O2) of the sum of all measured metals (Zn excluded) during the biomass combustion tests ranged from 57 μg Nm-3 for birch stemwood to 198 μg Nm-3 for birch bark. The concentration of Zn in the flue gas was generally considerably higher than those of the other metals, ranging from 646 μg Nm-3 for spruce/pine stemwood to 7948 μg Nm-3 for birch bark. Compared with coal and peat, the biomass fuels produced higher Zn emissions, but lower or similar emissions of the sum of the other metals. The volatile behavior and concentration of the metal in the flue gases as a function of the heavy metal in the fuel are also presented for selected heavy metals. © 2013 American Chemical Society.

  • 38.
    Wiinikka, Henrik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Grönberg, C.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Öhrman, Olov.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Boström, D.
    Influence of TiO2 additive on vaporization of potassium during straw combustion2009In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 23, no 11, p. 5367-5374Article in journal (Refereed)
    Abstract [en]

    In this work, the influence of TiO2 on the vaporization of K during combustion of straw under fixed bed condition was investigated experimentally. Controlled combustion experiments with a varied amount of TiO2 in straw pellets were performed in an 8 kWpellet burner together with sampling of particles (impactor and absolute filter), analysis of the flue gas composition (Fourier transform infrared, FTIR), and chemical analyses of the collected particles and bottom ash (inductively coupled plasma-atomic emission spectroscopy (ICP-AES), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), and X-ray diffraction (XRD)). The experimental results showed that the vaporization of K from the fuel bed was significantly reduced when TiO2 was used as an additive. The vaporization ofKwas reduced by∼40-50% for an optimal amount of TiO2 additive. The optimal added TiO2 for the straw used in this work corresponds to a Ti/K (wt) ratio between ∼0.6-1.0. If more TiO2 was added to the fuel, the release ofKto the gas phase was not further reduced and unreacted TiO 2 was found in the bottom ash. © 2009 American Chemical Society.

  • 39.
    Ögren, Yngve
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center. Luleå University of Technology,Sweden.
    Sepman, Alexey
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Qu, Zhechau
    Umeå University, Sweden.
    Schmidt, Florian M.
    Umeå University, Sweden.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center. Luleå University of Technology, Sweden.
    Comparison of Measurement Techniques for Temperature and Soot Concentration in Premixed, Small-Scale Burner Flames2017In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 31, no 10, p. 11328-11336Article in journal (Refereed)
    Abstract [en]

    Optical and intrusive measurement techniques for temperature and soot concentration in hot reacting flows were tested on a small-scale burner in fuel-rich, oxygen-enriched atmospheric flat flames produced to simulate the environment inside an entrained flow reactor. The optical techniques comprised two-color pyrometry (2C-PYR), laser extinction (LE), and tunable diode laser absorption spectroscopy (TDLAS), and the intrusive methods included fine-wire thermocouple thermometry (TC) and electrical low pressure impactor (ELPI) particle analysis. Vertical profiles of temperature and soot concentration were recorded in flames with different equivalence and O2/N2 ratios. The 2C-PYR and LE data were derived assuming mature soot. Gas temperatures up to 2200 K and soot concentrations up to 3 ppmv were measured. Close to the burner surface, the temperatures obtained with the pyrometer were up to 300 K higher than those measured by TDLAS. Further away from the burner, the difference was within 100 K. The TC-derived temperatures were within 100 K from the TDLAS results for most of the flames. At high signal-to-noise ratio and in flame regions with mature soot, the temperatures measured by 2C-PYR and TDLAS were similar. The soot concentrations determined with 2C-PYR were close to those obtained with LE but lower than the ELPI results. It is concluded that the three optical techniques have good potential for process control applications in combustion and gasification processes. 2C-PYR offers simpler installation and 2D imaging, whereas TDLAS and LE provide better accuracy and dynamic range without calibration procedures.

1 - 39 of 39
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
v. 2.34.0