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  • 1. Trubetskaya, Anna
    Fast pyrolysis of biomass at high temperatures2016Other (Other academic)
  • 2. Trubetskaya, Anna
    et al.
    Beckmann, Gert
    Jensen, Peter Arendt
    Jensen, Anker Degn
    Glarborg, Peter
    A way of a single biomass particle shape characterization in a CFD model2014Other (Other academic)
  • 3.
    Trubetskaya, Anna
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Kling, J.
    Brown, A.
    Tompsett, G.
    Umeki, K.
    Effects of Lignocellulosic Compounds on the Yield, Nanostructure and Reactivity of Soot from Fast Pyrolysis at High Temperatures2017Conference paper (Other academic)
  • 4.
    Trubetskaya, Anna
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Larsen Andersen, Mogens
    Talbro Barsberg, Søren
    Modeling of radical structures in biochar using DFT calculations2017In: ECI Digital Archives / [ed] Franco Berruti, Raffaella Ocone and Ondrej Masek, Digital Commons , 2017Conference paper (Other academic)
    Abstract [en]

    Carbon is a key ingredient for producing metals used for cellphones, laptop computers, photovoltaic panels, and related solid state silicon devices employed by mankind. Thus, introduction of an alternative reductant based on bioresources into steel manufacturing without significant investments in a new technology is of high importance and wide impact. The production of iron, steel, and many other metals can employ biocarbon as the needed reductant; but because of cost, coals are usually used instead. The anthropogenic CO2 emissions can be decreased by substitution of biochar in the production of silicon and metals due to the lower regeneration time of biomass < 10 years compared to 106-107 years for bituminous coal.

    This study aims to develop and to provide knowledge on the biochar structure at the molecular level including the presence of free radicals and oxygen heteroatoms that is essential for the understanding and prediction of biochar valuable properties in metallurgical applications. Both yields and biochar properties are important parameters for the optimization of pyrolysis conditions. Therefore, the pyrolysis conditions for the biochar application as a reducing agent in steel industry were optimized, and the molecular structure of the biochar by the combined use of experimental chemistry (Raman spectroscopy and Fourier transform infrared spectroscopy) and quantum chemistry computations (Density Functional Theory methods) was modified.

    The results indicated the formation of stable radicals from biomass pyrolysis at their termination stage which were quantified by the electron spin resonance spectroscopy. Based on the experimental and fitting results, PAH structures were selected as initial compounds for the DFT modeling. The comparison of hydroxylated with methylated PAH structures showed that hydroxylated PAH are excellent candidate to represent the radical structure based on the low bond dissociation energes. The bond dissociation energy of -10 Kcal mol-1 is in the range of the best known antioxidants. The results showed that the present DFT model predicts reasonably the biochar molecular structure, and can capture changes in the biochar molecular structure under different pyrolysis conditions.

  • 5.
    Trubetskaya, Anna
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Brown, Avery
    Tompsett, Geoffrey A.
    Timko, Michael T.
    Kling, Jens
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Larsen Andersen, Mogens
    Umeki, Kentaro
    Characterization and reactivity of soot from fast pyrolysis of lignocellulosic compounds and monolignols2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 212, p. 1489-1500Article in journal (Refereed)
    Abstract [en]

    This study presents the effect of lignocellulosic compounds and monolignols on the yield, nanostructure and reactivity of soot generated at 1250 °C in a drop tube furnace. The structure of soot was characterized by electron microscopy techniques, Raman spectroscopy and electron spin resonance spectroscopy. The CO2 reactivity of soot was investigated by thermogravimetric analysis. Soot from cellulose was more reactive than soot produced from extractives, lignin and monolignols. Soot reactivity was correlated with the separation distances between adjacent graphene layers, as measured using transmission electron microscopy. Particle size, free radical concentration, differences in a degree of curvature and multi-core structures influenced the soot reactivity less than the interlayer separation distances. Soot yield was correlated with the lignin content of the feedstock. The selection of the extraction solvent had a strong influence on the soot reactivity. The Soxhlet extraction of softwood and wheat straw lignin soot using methanol decreased the soot reactivity, whereas acetone extraction had only a modest effect.

  • 6. Trubetskaya, Anna
    et al.
    Jensen, Anker Degn
    Experimental investigations and modeling of devolatilization based on superimposed kinetics of biomass2016Other (Other academic)
  • 7. Trubetskaya, Anna
    et al.
    Jensen, Anker Degn
    Andersen, Mogens Larsen
    Talbro Barsberg, Søren
    Characterization of Free Radicals By Electron Spin Resonance Spectroscopy in Biochars from Pyrolysis at High Heating Rates and at High Temperatures2016Other (Other academic)
  • 8. Trubetskaya, Anna
    et al.
    Jensen, Peter Arendt
    Glarborg, Peter
    Garcia Llamas, Angel David
    Umeki, Kentaro
    Kling, Jens
    Gardini, Diego
    Bates, Richard B.
    Jensen, Anker Degn
    Effects of Biomass Feedstock on the Yield and Reactivity of Soot from Fast Pyrolysis at High Temperatures2016Other (Other academic)
  • 9.
    Trubetskaya, Anna
    et al.
    Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltoft Plads, Building 229, Kgs. Lyngby 2800, Denmark.
    Jensen, Peter Arendt
    Jensen, Anker Degn
    Llamas, Angel David Garcia
    Umeki, Kentaro
    Gardini, Diego
    Kling, Jens
    Bates, Richard B.
    Glarborg, Peter
    Effects of several types of biomass fuels on the yield, nanostructure and reactivity of soot from fast pyrolysis at high temperatures2016In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 171, p. 468-482Article in journal (Refereed)
    Abstract [en]

    This study presents the effect of biomass origin on the yield, nanostructure and reactivity of soot. Soot was produced from wood and herbaceous biomass pyrolysis at high heating rates and at temperatures of 1250 and 1400 °C in a drop tube furnace. The structure of solid residues was characterized by electron microscopy techniques, X-ray diffraction and N2 adsorption. The reactivity of soot was investigated by thermogravimetric analysis. Results showed that soot generated at 1400 °C was more reactive than soot generated at 1250 °C for all biomass types. Pinewood, beechwood and wheat straw soot demonstrated differences in alkali content, particle size and nanostructure. Potassium was incorporated in the soot matrix and significantly influenced soot reactivity. Pinewood soot particles produced at 1250 °C had a broader particle size range (27.2–263 nm) compared to beechwood soot (33.2–102 nm) and wheat straw soot (11.5–165.3 nm), and contained mainly multi-core structures.

  • 10.
    Trubetskaya, Anna
    et al.
    Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads Bygning 229, Kgs. Lyngby 2800, Denmark.
    Jensen, Peter Arendt
    Jensen, Anker Degn
    Llamas, Angel David Garcia
    Umeki, Kentaro
    Glarborg, Peter
    Effect of fast pyrolysis conditions on biomass solid residues at high temperatures2016In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 143, p. 118-129Article in journal (Refereed)
    Abstract [en]

    Fast pyrolysis of wood and straw was conducted in a drop tube furnace (DTF) and compared with corresponding data from a wire mesh reactor (WMR) to study the influence of temperature (1000-1400)°C, biomass origin (pinewood, beechwood, wheat straw, alfalfa straw), and heating rate (103 °C/s, 104 °C/s) on the char yield and morphology. Scanning electron microscopy (SEM), elemental analysis, and ash compositional analysis were applied to characterize the effect of operational conditions on the solid residues (char, soot) and gaseous products. The char yield from fast pyrolysis in the DTF setup was 3 to 7% (daf) points lower than in the WMR. During fast pyrolysis pinewood underwent drastic morphological transformations, whereas beechwood and straw samples retained the original porous structure of the parental fuel with slight melting on the surface. The particle size of Danish wheat straw char decreased in its half-width with respect to the parental fuel, whereas the alfalfa straw char particle size remained unaltered at higher temperatures. Soot particles in a range from 60 to 300 nm were obtained during fast pyrolysis. The soot yield from herbaceous fuels was lower than from wood samples, possibly due to differences in the content of lignin and resin acids.

  • 11. Trubetskaya, Anna
    et al.
    Jensen, Peter Arendt
    Jensen, Anker Degn
    Steibel, Markus
    Spliethoff, Hartmut
    Glarborg, Peter
    Influence of fast pyrolysis conditions on yield and structural transformation of biomass chars2015In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 140, p. 205-214Article in journal (Refereed)
    Abstract [en]

    Fast pyrolysis of biomass (wood, straw, rice husk) and its major components (cellulose, hemicellulose, lignin) was conducted in a wire mesh reactor. The aim of this study was to understand the influence of temperature (350-1400 ∗ C), heating rate (10-3000 ∗ C/s), particle size (0.05-2 mm) and holding time (1-4 s) on the char morphology and char yield. Scanning electron microscopy (SEM) and elemental analysis were conducted to determine the effect of operating conditions on char softening and melting during pyrolysis. The char yield decreased with heating rate for rates ≤ 600 ∗ C/s; above this value a similar biomass char yield was obtained. The potassium content affected the char yield stronger than other minerals, while the distribution of the three major biomass constituents (cellulose, hemicellulose, lignin) affected the char yield only to a minor degree. Moreover, it was found that the heat treatment temperature had a larger influence on the char yield than the heating rate. Scanning electron microscopy indicated different types of biomass char plasticization influenced by the applied temperatures, heating rates, particle sizes and holding times, except for the rice husk char that formed chars with a structure similar to the parental fuel at all conditions. The less severe morphological changes of rice husk char were attributed to a high silica content.

  • 12. Trubetskaya, Anna
    et al.
    Jensen, Peter Arendt
    Jensen, Anker Degn
    Stiebel, Markus
    Spliethoff, Hartmuth
    Glarborg, Peter
    Larsen, Flemming Hoffmann
    Comparison of high temperature chars of wheat straw and rice husk with respect to chemistry, morphology and reactivity2016In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 86, p. 76-87Article in journal (Refereed)
    Abstract [en]

    Fast pyrolysis of wheat straw and rice husk was carried out in an entrained flow reactor at high-temperatures (1000–1500) °C. The collected char was analyzed using X-ray diffractometry, N2-adsorption, scanning electron microscopy, particle size analysis with CAMSIZER XT, 29Si and 13C solid-state nuclear magnetic resonance spectroscopy and thermogravimetric analysis to investigate the effect of inorganic matter on the char morphology and oxygen reactivity. The silicon compounds were dispersed throughout the turbostratic structure of rice husk char in an amorphous phase with a low melting temperature (≈730 °C), which led to the formation of a glassy char shell, resulting in a preserved particle size and shape of chars. The high alkali content in the wheat straw resulted in higher char reactivity, whereas the lower silicon content caused variations in the char shape from cylindrical to near-spherical char particles. The reactivities of pinewood and rice husk chars were similar with respect to oxidation, indicating less influence of silicon oxides on the char reactivity.

  • 13.
    Trubetskaya, Anna
    et al.
    Department of Energy Engineering, Luleå University of Technology, Luleå 97187, Sweden.
    Poyraz, Yunus
    Weber, Roman
    Wadembäck, Johan
    Secondary comminution of wood pellets in power plant and laboratory-scale mills2017In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 160, p. 216-227Article in journal (Refereed)
    Abstract [en]

    This study aims to determine the influence of mill type and pellet wood composition on particle size and shape of milled wood. The size and shape characteristics of pellets comminuted using power plant roller mills were compared with those obtained by using laboratory-scale roller- and hammer mills. A 2D dynamic imaging device was used for particle characterization. It was shown that mill type has a significant impact on particle size but an almost negligible effect on the shape of milled wood. Comminution in the pilot plant using a Loesche roller mill requires less energy than using a hammer mill, but generates a larger fraction of coarse particles. The laboratory-scale roller mill provides comparable results with the power plant roller mill with respect to particle size and shape.

  • 14. Trubetskaya, Anna
    et al.
    Stiebel, Markus
    Spliethoff, Hartmuth
    Jensen, Anker Degn
    Glarborg, Peter
    Effect of pyrolysis conditions and composition on the char structure and char yield of biomass chars2014Other (Other academic)
  • 15. Trubetskaya, Anna
    et al.
    Stiebel, Markus
    Spliethoff, Hartmuth
    Talbro Barsberg, Søren
    Andersen, Mogens Larsen
    Jensen, Peter Arendt
    Jensen, Anker Degn
    Glarborg, Peter
    Structural and Compositional Transformations of Biomass Chars during Fast Pyrolysis2014Other (Other academic)
  • 16.
    Trubetskaya, Anna
    et al.
    Energy Engineering Department, Luleå University of Technology, 97187 Luleå, Sweden.
    Surup, Gerrit
    Shapiro, Alexander
    Bates, Richard B.
    Modeling the influence of potassium content and heating rate on biomass pyrolysis2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 194, p. 199-211Article in journal (Refereed)
    Abstract [en]

    This study presents a combined kinetic and particle model that describes the effect of potassium and heating rate during the fast pyrolysis of woody and herbaceous biomass. The model calculates the mass loss rate, over a wide range of operating conditions relevant to suspension firing. The shrinking particle model considers internal and external heat transfer limitations and incorporates catalytic effects of potassium on the product yields. Modeling parameters were tuned with experimentally determined char yields at high heating rates (&gt;200 K s−1) using a wire mesh reactor, a single particle burner, and a drop tube reactor. The experimental data demonstrated that heating rate and potassium content have significant effects on the char yield. The importance of shrinkage on the devolatilization time becomes greater with increasing particle size, but showed little influence on the char yields.

  • 17. Trubetskaya, Anna
    et al.
    Umeki, Kentaro
    Garcia Llamas, Angel David
    jensen, Anker Degn
    Jensen, Peter Arendt
    Glarborg, Peter
    Effect of Fast Pyrolysis Conditions on Structural Transformation and Reactivity of Herbaceous Biomasses at High Temperatures2015Other (Other academic)
  • 18. Trubetskaya, Anna
    et al.
    Umeki, Kentaro
    Garcia Llamas, Angel David
    Jensen, Anker Degn
    Jensen, Peter Arendt
    Glarborg, Peter
    Effect of Fast Pyrolysis Conditions on the Biomass Solid Residues at High Temperatures (1000-1400°C)2015Other (Other academic)
1 - 18 of 18
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