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Publications (10 of 22) Show all publications
Trubetskaya, A., Hofmann Larsen, F., Shchukarev, A., Ståhl, K. & Umeki, K. (2018). Potassium and soot interaction in fast biomass pyrolysis at high temperatures. Fuel, 225, 89-94
Open this publication in new window or tab >>Potassium and soot interaction in fast biomass pyrolysis at high temperatures
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2018 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 225, p. 89-94Article in journal (Refereed) Published
Abstract [en]

his study aims to investigate the interaction between potassium and carbonaceous matrix of soot produced from wood and herbaceous biomass pyrolysis at high heating rates at 1250°C in a drop tube reactor. The influence of soot carbon chemistry and potassium content in the original biomass on the CO2 reactivity was studied by thermogravimetric analysis. The XPS results showed that potassium incorporation with oxygen-containing surface groups in the soot matrix did not occur during high temperature pyrolysis. The potassium was mostly found as water-soluble salts such as KCl, KOH, KHCO3 and K2CO3 in herbaceous biomass soot. The low ash-containing pinewood soot was less reactive than the potassium rich herbaceous biomass soot, indicating a dominating role of potassium on the soot reactivity. However, the catalytic effect of potassium on the reactivity remained the same after a certain potassium amount was incorporated in the soot matrix during pyrolysis. Raman spectroscopy results showed that the carbon chemistry of biomass soot also affected the CO2 reactivity. The less reactive pinewood soot was more graphitic than herbaceous biomass soot samples with the disordered carbon structure.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Engineering and Technology Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-68116 (URN)10.1016/j.fuel.2018.03.140 (DOI)000432922400011 ()2-s2.0-85044460207 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-04-03 (andbra)

Available from: 2018-04-02 Created: 2018-04-02 Last updated: 2018-06-07Bibliographically approved
Trubetskaya, A. & Umeki, K. (2017). Chracterization and prediction of tar formation from fast pyrolysis of lignin. In: Combustion Flame Days 2017: . Paper presented at Combustion Flame Days, Stockholm, 10-11 October 2017.
Open this publication in new window or tab >>Chracterization and prediction of tar formation from fast pyrolysis of lignin
2017 (English)In: Combustion Flame Days 2017, 2017Conference paper, Oral presentation with published abstract (Refereed)
National Category
Chemical Engineering Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-64686 (URN)
Conference
Combustion Flame Days, Stockholm, 10-11 October 2017
Available from: 2017-06-30 Created: 2017-06-30 Last updated: 2017-11-24Bibliographically approved
Trubetskaya, A., Broström, M. & Talbro Barsberg, S. (2017). Development of CO2 neutral reductants in metallurgical industry from thermochemically produced biochar using DFT calculations. In: Biochar: Production, Characterization and Applications: August 20-25, 2017, Hotel Calissano Alba, Italy. Paper presented at ECI Meeting, Alba, Italy, August 20-25, 2017.
Open this publication in new window or tab >>Development of CO2 neutral reductants in metallurgical industry from thermochemically produced biochar using DFT calculations
2017 (English)In: Biochar: Production, Characterization and Applications: August 20-25, 2017, Hotel Calissano Alba, Italy, 2017Conference paper, Oral presentation with published abstract (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 metalscan employ biocarbon as the needed reductant; but because of cost, coals are usually used instead. The anthropogenic CO2emissions 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 106-107years 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(DFT)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 candidates to represent the radical structure based on the low bond dissociation energies. The bond dissociation energy of -10 Kcal mol-1is in the range of the best know antioxidants. The results showed that the present DFT model predicts reasonable the biochar molecular structure, and can capture changes in the biochar molecular structure under different pyrolysis conditions

National Category
Chemical Engineering Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-64685 (URN)
Conference
ECI Meeting, Alba, Italy, August 20-25, 2017
Available from: 2017-06-30 Created: 2017-06-30 Last updated: 2017-11-24Bibliographically approved
Trubetskaya, A., Broström, M., Kling, J., Brown, A., Tompsett, G. & Umeki, K. (2017). Effects of Lignocellulosic Compounds on the Yield, Nanostructure and Reactivity of Soot from Fast Pyrolysis at High Temperatures. In: : . Paper presented at Nordic Flame Days, Stockholm, 10-11 October 2017.
Open this publication in new window or tab >>Effects of Lignocellulosic Compounds on the Yield, Nanostructure and Reactivity of Soot from Fast Pyrolysis at High Temperatures
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2017 (English)Conference paper, Oral presentation with published abstract (Other academic)
Abstract [en]

Gasification offers the utilization of biomass to a wide variety of applications such as heat, electricity, chemicals and transport fuels in an efficient and sustainable manner. High soot yields in the high-temperature entrained flow gasification lead to intensive gas cleaning and can cause a possible plant shut down. The reduction of soot formation increases the overall production system efficiency and improves the economic feasibility and reliability of the gasification plant. The aim of this work is to present the effect of lignocellulosic compoundson the yield, nanostructure and reactivity of soot. Soot was produced from holocelluloses, extractives, two types of organosolv lignin (softwood and wheat straw), and lignin-derived compounds (syringol, guaiacol, p-hydroxyphenol)at temperature of 1250°Cand residence time of 0.17 sand 0.35 sin a drop tube furnace.Soxhlet extraction was performed on soot samples from pyrolysis of both lignin samplesusing acetone and methanol as a solvent.The structure of solid residues was characterized by transmission electron microscopy and Raman spectroscopy. The reactivity of soot inO2oxidation and CO2gasificationwas investigated by thermogravimetric analysis. The present results indicated that soot yields from pyrolysis of ligninfrom softwood and extractives at 1250°C with the residence time of 0.17 swere similaras shown in Figure 1. The highest soot yield was obtained from pyrolysis of wheat straw lignin and quantitatively comparable with the soot yield of hydroquinone. The presence of hydroxyl groups compared to other lignin-derived compounds representing S-and G-lignin types might enhance the soot formation.Lower soot yields were obtained from pyrolysis of cellulose and hemicellulosedue to the lower presence of inherent aromatic rings [1-3].Moreover, the soot yields from pyrolysis of potassium impregnated lignin at 1250°C with the residence time of 0.35 swere significantly lower than that of non-treated lignin samples indicating the catalytic influence of potassium inhibitinggrowth of polycyclic aromatic hydrocarbons, confirming the previous results of Umeki et al. [4]

National Category
Chemical Engineering Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-64687 (URN)
Conference
Nordic Flame Days, Stockholm, 10-11 October 2017
Available from: 2017-06-30 Created: 2017-06-30 Last updated: 2017-11-24Bibliographically approved
Trubetskaya, A., Surup, G., Shapiro, A. & Bates, R. B. (2017). Modeling the influence of potassium content and heating rate on biomass pyrolysis. Applied Energy, 194, 199-211
Open this publication in new window or tab >>Modeling the influence of potassium content and heating rate on biomass pyrolysis
2017 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 194, p. 199-211Article in journal (Refereed) Published
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 (>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.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-62525 (URN)10.1016/j.apenergy.2017.03.009 (DOI)000399623600016 ()2-s2.0-85015080162 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-03-15 (andbra)

Available from: 2017-03-15 Created: 2017-03-15 Last updated: 2018-09-13Bibliographically approved
Trubetskaya, A., Beckmann, G., Wadenbäck, J., Holm, J. K., Velaga, S. & Weber, R. (2017). One way of representing the size and shape of biomass particles in combustion modeling [Review]. Fuel, 206, 675-683
Open this publication in new window or tab >>One way of representing the size and shape of biomass particles in combustion modeling
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2017 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 206, p. 675-683Article, book review (Refereed) Published
Abstract [en]

This study aims to provide a geometrical description of biomass particles that can be used in combustion models. The particle size of wood and herbaceous biomass was compared using light microscope, 2D dynamic imaging, laser diffraction, sieve analysis and focused beam reflectance measurement. The results from light microscope and 2D dynamic imaging analysis were compared and it showed that the data on particle width, measured by these two techniques, were identical. Indeed, 2D dynamic imaging was found to be the most convenient particle characterization method, providing information on both the shape and the external surface area. Importantly, a way to quantify all three dimensions of biomass particles has been established. It was recommended to represent a biomass particle in combustion models as an infinite cylinder with the volume-to-surface ratio (V/A) measured using 2D dynamic imaging.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Chemical Engineering Energy Engineering Other Health Sciences
Research subject
Energy Engineering; Health Science
Identifiers
urn:nbn:se:ltu:diva-64684 (URN)10.1016/j.fuel.2017.06.052 (DOI)000405805800066 ()2-s2.0-84992456215 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-06-03 (andbra)

Available from: 2017-06-30 Created: 2017-06-30 Last updated: 2018-07-10Bibliographically approved
Trubetskaya, A., Surup, G., Shapiro, A. & Bates, R. B. (2017). Publisher’s Note to Modeling the influence of potassium content and heating rate on biomass pyrolysis [Appl. Energy J. 194 (2017) 199–211] [Letter to the editor]. Applied Energy, 202, 785
Open this publication in new window or tab >>Publisher’s Note to Modeling the influence of potassium content and heating rate on biomass pyrolysis [Appl. Energy J. 194 (2017) 199–211]
2017 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 202, p. 785p. 785-Article in journal, Letter (Other academic) Published
Place, publisher, year, edition, pages
Elsevier, 2017. p. 785
National Category
Mathematics Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-64930 (URN)10.1016/j.apenergy.2017.07.012 (DOI)000407188500065 ()
Available from: 2017-08-01 Created: 2017-08-01 Last updated: 2018-07-10Bibliographically approved
Trubetskaya, A., Poyraz, Y., Weber, R. & Wadenbäck, J. (2017). Secondary comminution of wood pellets in power plant and laboratory-scale mills. Fuel processing technology, 160, 216-227
Open this publication in new window or tab >>Secondary comminution of wood pellets in power plant and laboratory-scale mills
2017 (English)In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 160, p. 216-227Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-62484 (URN)10.1016/j.fuproc.2017.02.023 (DOI)000399256600027 ()2-s2.0-85015632779 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-03-14 (andbra)

Available from: 2017-03-14 Created: 2017-03-14 Last updated: 2018-09-13Bibliographically approved
Trubetskaya, A., Jensen, P. A., Jensen, A. D., Glarborg, P., Larsen, F. H. & Andersen, M. L. (2016). Characterization of free radicals by Electron Spin Resonance Spectroscopy in biochars from pyrolysis at high heating rates and at high temperatures. Biomass and Bioenergy, 94, 117-129
Open this publication in new window or tab >>Characterization of free radicals by Electron Spin Resonance Spectroscopy in biochars from pyrolysis at high heating rates and at high temperatures
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2016 (English)In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 94, p. 117-129Article in journal (Refereed) Published
Abstract [en]

The concentration and type of free radicals from the decay (termination stage) of pyrolysis at slow and fast heating rates and at high temperatures (above 1000°C) in biomass char have been studied. A room-temperature electron spin resonance spectroscopy study was conducted on original wood, herbaceous biomass, holocelluloses, lignin and their chars, prepared at high temperatures in a wire mesh reactor, an entrained flow reactor, and a tubular reactor. The radical concentrations in the chars from the decay stage range up between 7·1016 and 1.5·1018 spins g−1. The results indicated that the biomass major constituents (cellulose, hemicellulose, lignin) had a minor effect on remaining radical concentrations compared to potassium and silica contents. The higher radical concentrations in the wheat straw chars from the decay stage of pyrolysis in the entrained flow reactor compared to the wood chars were related to the decreased mobility of potassium in the char matrix, leading to the less efficient catalytic effects of potassium on the bond-breaking and radical re-attachments. The high Si levels in the rice husk caused an increase in the char radical concentration compared to the wheat straw because the free radicals were trapped in a char consisting of a molten amorphous silica at heating rates of 103–104 K s−1. The experimental electron spin resonance spectroscopy spectra were analyzed by fitting to simulated data in order to identify radical types, based on g-values and line widths. The results show that at high temperatures, mostly aliphatic radicals (g = 2.0026–2.0028) and PAH radicals (g = 2.0027–2.0031) were formed.

National Category
Chemical Process Engineering Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-62631 (URN)10.1016/j.biombioe.2016.08.020 (DOI)
Available from: 2017-03-22 Created: 2017-03-22 Last updated: 2017-11-29Bibliographically approved
Trubetskaya, A., Jensen, A. D., Andersen, M. L. & Talbro Barsberg, S. (2016). Characterization of Free Radicals By Electron Spin Resonance Spectroscopy in Biochars from Pyrolysis at High Heating Rates and at High Temperatures. In: : . Paper presented at 2016 AIChE Annual Meeting, San Francisco, CA, United States, 13-18 November 2016.
Open this publication in new window or tab >>Characterization of Free Radicals By Electron Spin Resonance Spectroscopy in Biochars from Pyrolysis at High Heating Rates and at High Temperatures
2016 (English)Conference paper, Oral presentation with published abstract (Refereed)
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-62716 (URN)
Conference
2016 AIChE Annual Meeting, San Francisco, CA, United States, 13-18 November 2016
Available from: 2017-03-27 Created: 2017-03-27 Last updated: 2017-11-24Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-6571-3277

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