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  • 1.
    Wagner, Katharina
    et al.
    Bioenergy 2020+ GmbH,Vienna, Austria. Institute of Chemical, Environmental & Bioscience Engineering, Technische Universität Wien, Vienna, Austria.
    Häggström, Gustav
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Skoglund, Nils
    Bioenergy 2020+ GmbH,Vienna, Austria. Institute of Chemical, Environmental & Bioscience Engineering, Technische Universität Wien, Vienna, Austria.Thermochemical Energy Conversion Laboratory, Umeå University,Umeå, Sweden.
    Priscak, Juraj
    Bioenergy 2020+ GmbH,Vienna, Austria. Institute of Chemical, Environmental & Bioscience Engineering, Technische Universität Wien, Vienna, Austria.
    Kuba, Matthias
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. Bioenergy 2020+ GmbH,Vienna, Austria. Institute of Chemical, Environmental & Bioscience Engineering, Technische Universität Wien, Vienna, Austria.Thermochemical Energy Conversion Laboratory, Umeå University, Umeå, Sweden.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Hofbauer, Hermann
    Institute of Chemical, Environmental & Bioscience Engineering, Technische Universität Wien, Vienna, Austria.
    Layer formation mechanism of K-feldspar in bubbling fluidized bed combustion of phosphorus-lean and phosphorus-rich residual biomass2019In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 248, p. 545-554Article in journal (Refereed)
    Abstract [en]

    The use of phosphorus-rich fuels in fluidized bed combustion is one probable way to support both heat and power production and phosphorus recovery. Ash is accumulated in the bed during combustion and interacts with the bed material to form layers and/or agglomerates, possibly removing phosphorus from the bed ash fraction. To further deepen the knowledge about the difference in the mechanisms behind the ash chemistry of phosphorus-lean and phosphorus-rich fuels, experiments in a 5 kW bench-scale-fluidized bed test-rig with K-feldspar as the bed material were conducted with bark, wheat straw, chicken manure, and chicken manure admixtures to bark and straw. Bed material samples were collected and studied for layer formation and agglomeration phenomena by scanning electron microscopy combined with energy dispersive X-ray spectrometry. The admixture of phosphorus-rich chicken manure to bark changed the layer formation mechanism, shifting the chemistry to the formation of phosphates rather than silicates. The admixture of chicken manure to straw reduced the ash melting and agglomeration risk, making it possible to increase the time until defluidization of the fluidized bed occurred. The results also highlight that an increased ash content does not necessarily lead to more ash melting related problems if the ash melting temperature is high enough.

  • 2.
    Wagner, Katharina
    et al.
    Bioenergy 2020+ GmbH, Güssing, Austria.Institute of Chemical, Environmental & Bioscience Engineering, TU Wien, Vienna, Austria.
    Häggström, Gustav
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Mauerhofer, Anna Magdalena
    Institute of Chemical, Environmental & Bioscience Engineering, TU Wien, Vienna, Austria.
    Kuba, Matthias
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. Bioenergy 2020+ GmbH, Güssing, Austria. Institute of Chemical, Environmental & Bioscience Engineering, TU Wien, Vienna, Austria.Thermochemical Energy Conversion Laboratory, Department of Applied Physics and Electronics, Umeå University, Umeå, Sweden .
    Skoglund, Nils
    Thermochemical Energy Conversion Laboratory, Department of Applied Physics and Electronics, Umeå University, Umeå, Sweden.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Hofbauer, Hermann
    Institute of Chemical, Environmental & Bioscience Engineering, TU Wien, Vienna, Austria.
    Layer formation on K-feldspar in fluidized bed combustion and gasification of bark and chicken manure2019In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 127, article id 105251Article in journal (Refereed)
    Abstract [en]

    Understanding layer formation on bed materials used in fluidized beds is a key step for advances in the application of alternative fuels. Layers can be responsible for agglomeration-caused shut-downs but they can also improve the gas composition in fluidized bed gasification. Layers were observed on K-feldspar (KAlSi3O8) impurities originating from the combined heat and power plant Senden which applies the dual fluidized bed (DFB) steam gasification technology. Pure K-feldspar was therefore considered as alternative bed material in DFB steam gasification. Focusing on the interactions between fuel ash and bed material, K-feldspar was tested in combustion and DFB steam gasification atmospheres using different fuels, namely Ca-rich bark, Ca- and P-rich chicken manure, and an admixture of chicken manure to bark. The bed particle layers formed on the bed material surface were characterized using combined scanning electron microscopy and energy-dispersive X-ray spectroscopy; area mappings and line scans were carried out for all samples. The obtained data show no essential influence of operational mode on the layer-formation process. During the combustion and DFB steam gasification of Ca-rich bark, a layer rich in Ca formed while K was diffusing out of the layer. The use of Ca- and P-rich chicken manure inhibited the diffusion of K, and a layer rich in Ca and P formed. The addition of P to bark via chicken manure also changed the underlying layer-formation processes to reflect the same processes as observed for pure chicken manure.

  • 3.
    Wagner, Katharina
    et al.
    Bioenergy 2020+ GmbH.
    Kuba, Mathias
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. Bioenergy 2020+ GmbH.
    Häggström, Gustav
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Skoglund, Nils
    Thermochemical Energy Conversion Laboratory, Department of Applied Physics and Electronics, Umeå University.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Hofbauer, Hermann
    Institute of Chemical, Environmental & Bioscience Engineering, TU Wien.
    Influence of phosphorus on the layer formation on k-feldspar during fluidized bed combustion and gasification2018In: European biomass conference and exhibition proceedings, E-ISSN 2282-5819, Vol. 26thEUBCE, p. 486-492Article in journal (Refereed)
    Abstract [en]

    Today, mainly wood-based feedstocks are used in thermo-chemical biomass conversion since they have a comparably high heating value and contain a small amount of ash. Fluidized beds allow a greater variety of fuels to be used, since they are rather flexible regarding their fuel input. The use of biogenic waste streams (chicken manure, horse manure, etc.) and sewage sludge would not only increase the fuel diversity in fluidized beds but might also enhance the usability of side products. The contained essential nutrients like phosphorus, potassium, calcium, etc. in these fuels are enriched in the ash after thermochemical conversion. Thus, in the near future it may be possible to apply this ash as secondary resource for fertilizer. Especially the recovery of phosphorus is of importance due to the imminent phosphorus scarcity. Due to its tendency to react with ash forming elements in fuels, phosphorus influences the ash chemistry severely. Especially the agglomeration and layer formation on bed materials during biomass combustion and gasification is highly dependent on the predominant ash forming elements. Phosphorus therefore has a significant impact on those mechanisms. Until now, the behavior of phosphorus-rich fuels in fluidized beds has not been studied in much detail. To develop a basic understanding of the behavior, phosphorus-rich feedstock was combusted in a bench-scale fluidized bed reactor. Ash layers on bed particles, which were formed during these experiments, were studied and compared to results with phosphorus-lean fuels. Furthermore, layer formation of phosphorus-rich and phosphorus-lean fuels from dual fluid bed gasification were compared to those from fluidized bed combustion. The studied layers on bed materials showed significant amounts of phosphorus. The data also indicates a change in layer formation as soon as phosphorus is present. An increased catalytic activity due ash-layer formation was observed for both phosphorus-rich and phosphorus-lean feedstock, independent from the presence of phosphorus in the ash layer

  • 4.
    Kirtania, Kawnish
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Häggström, Gustav
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Broström, Markus
    Umeå University, Department of Applied Physics and Electronics, Thermochemical Energy Conversion Laboratory,.
    Umeki, Kentaro
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Furusjö, Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Cogasification of crude glycerol and black liquor blends: char morphology and gasification kinetics2017In: Energy Technology, ISSN 2194-4296, Vol. 5, no 8, p. 1272-1281Article in journal (Refereed)
    Abstract [en]

    This study assesses the feasibility of black liquor/glycerol blends as potential gasification feedstock. The char gasification reactivity and kinetics were studied at T = 750 °C, 800 °C, 850 °C and 900 °C for 20% and 40% blends of glycerol with black liquor. Three qualities of glycerol were used including two industrial grade crude glycerols. Gasification rates were similar for all blends, indicating sufficient alkali metal catalysis also for the char blends (Alkali/C atomic ratio between 0.45 and 0.55). The blends with the most impure glycerol (containing K) were found to have the lowest activation energies (~120 kJ/mol) and reaction times for char gasification indicating fuel properties suitable for gasification. Char particles from different blends showed similar surface morphology as black liquor chars with even surface distribution of alkali elements. A loss of alkali (mainly, K) from the fuel blends during pyrolysis indicated the necessity to perform gas-phase studies of alkali release. Overall, these results encourage the use of glycerol as a potential gasification feedstock for catalytic gasification based bio-refineries.  

  • 5.
    Umeki, Kentaro
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Häggström, Gustav
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bach-Oller, Albert
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Kirtania, Kawnish
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Furusjö, Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Reduction of tar and soot formation from entrained-flow gasification of woody biomass by alkali impregnation2017In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 31, no 5, p. 5104-5110Article in journal (Refereed)
    Abstract [en]

    Tar and soot in product gas have been a major technical challenge toward the large-scale industrial installation of biomass gasification. This study aims at demonstrating that the formation of tar and soot can be reduced simultaneously using the catalytic activity of alkali metal species. Pine sawdust was impregnated with aqueous K2CO3 solution by wet impregnation methods prior to the gasification experiments. Raw and alkali-impregnated sawdust were gasified in a laminar drop-tube furnace at 900–1400 °C in a N2–CO2 mixture, because that creates conditions representative for an entrained-flow gasification process. At 900–1100 °C, char, soot and tar decreased with the temperature rise for both raw and alkali-impregnated sawdust. The change in tar and soot yields indicated that potassium inhibited the growth of polycyclic aromatic hydrocarbons and promoted the decomposition of light tar (with 1–2 aromatic rings). The results also indicated that the catalytic activity of potassium on tar decomposition exists in both solid and gas phases. Because alkali salts can be recovered from product gas as an aqueous solution, alkali-catalyzed gasification of woody biomass can be a promising process to produce clean product gas from the entrained-flow gasification process at a relatively low temperature.

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