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Strandberg, A., Skoglund, N. & Thyrel, M. (2019). Characterization of porosity and microstructure of phosphorus-rich ash particles with X-ray micro-tomography. In: : . Paper presented at Nordic Flame Days, Turku, Finland, 28-29 August, 2019.
Open this publication in new window or tab >>Characterization of porosity and microstructure of phosphorus-rich ash particles with X-ray micro-tomography
2019 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

A large proportion of the nutrients supplied from forest and agricultural sector are lost today, both through leaching and removing of produced biomass. Sustainable and efficient recycling of macro- and micro nutrients can be done by combustion / co-combustion of residual streams, which makes it possible to utilize for example the phosphorus-bound fraction in the produced ash for further processing and recycling. The porosity of the ash is important for, among other things, leaching and water-retaining ability when returning to the soil. The purpose of the project is to provide detailed knowledge of porosity and internal microstructure of ash particles from combustion of residual biomass streams, by using X-ray based micro-tomography and image analysis. The results provide new insights into how ash porosity and micro structure differs between different ashes, depending on fuel and the choice of conversion process.

National Category
Chemical Sciences Engineering and Technology
Identifiers
urn:nbn:se:umu:diva-163277 (URN)
Conference
Nordic Flame Days, Turku, Finland, 28-29 August, 2019
Available from: 2019-09-12 Created: 2019-09-12 Last updated: 2019-10-23Bibliographically approved
Skoglund, N. (2019). Inorganic chemistry and bioenergy - an unexpected match?. In: : . Paper presented at Inorganic Days, Umeå, Sweden, June 12-14, 2019.
Open this publication in new window or tab >>Inorganic chemistry and bioenergy - an unexpected match?
2019 (English)Conference paper, Oral presentation only (Other academic)
National Category
Inorganic Chemistry Other Chemistry Topics
Identifiers
urn:nbn:se:umu:diva-160830 (URN)
Conference
Inorganic Days, Umeå, Sweden, June 12-14, 2019
Available from: 2019-06-24 Created: 2019-06-24 Last updated: 2019-06-25Bibliographically approved
Wagner, K., Häggström, G., Skoglund, N., Priscak, J., Kuba, M., Öhman, M. & Hofbauer, H. (2019). Layer formation mechanism of K-feldspar in bubbling fluidized bed combustion of phosphorus-lean and phosphorus-rich residual biomass. Applied Energy, 248, 545-554
Open this publication in new window or tab >>Layer formation mechanism of K-feldspar in bubbling fluidized bed combustion of phosphorus-lean and phosphorus-rich residual biomass
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2019 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 248, p. 545-554Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Phosphorus, Layer formation, Agglomeration, K-feldspar, Fluidized bed
National Category
Energy Engineering Inorganic Chemistry
Identifiers
urn:nbn:se:umu:diva-160593 (URN)10.1016/j.apenergy.2019.04.112 (DOI)000469891900044 ()2-s2.0-85064643200 (Scopus ID)
Projects
Bio4Energy
Funder
The Kempe Foundations
Available from: 2019-06-24 Created: 2019-06-24 Last updated: 2019-09-02Bibliographically approved
Wagner, K., Haggstrom, G., Mauerhofer, A. M., Kuba, M., Skoglund, N., Ohman, M. & Hofbauer, H. (2019). Layer formation on K-feldspar in fluidized bed combustion and gasification of bark and chicken manure. Paper presented at 26th European Biomass Conference and Exhibition (EUBCE), MAY 14-17, 2018, Copenhagen, DENMARK. Biomass and Bioenergy, 127, Article ID UNSP 105251.
Open this publication in new window or tab >>Layer formation on K-feldspar in fluidized bed combustion and gasification of bark and chicken manure
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2019 (English)In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 127, article id UNSP 105251Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2019
Keywords
Fluidized bed, Layer formation, K-feldspar, Phosphorous, Combustion, DFB steam gasification
National Category
Chemical Process Engineering
Identifiers
urn:nbn:se:umu:diva-162319 (URN)10.1016/j.biombioe.2019.05.020 (DOI)000478564300032 ()
Conference
26th European Biomass Conference and Exhibition (EUBCE), MAY 14-17, 2018, Copenhagen, DENMARK
Available from: 2019-09-03 Created: 2019-09-03 Last updated: 2019-09-03Bibliographically approved
Pettersson, A., Nordin, A., Skoglund, N. & Åmand, L.-E. (2019). Phosphorous Rich Bottom Ash with Low Cadmium Content by Ash Design by means of Co-Combustion of Municipal Sewage Sludgein a 27MWth Grate Fired Boiler. In: : . Paper presented at Nordic Flame Days 2019, Åbo, Finland, August 28 - 29, 2019.
Open this publication in new window or tab >>Phosphorous Rich Bottom Ash with Low Cadmium Content by Ash Design by means of Co-Combustion of Municipal Sewage Sludgein a 27MWth Grate Fired Boiler
2019 (English)Conference paper, Oral presentation only (Refereed)
National Category
Other Chemical Engineering Energy Engineering
Identifiers
urn:nbn:se:umu:diva-163594 (URN)
Conference
Nordic Flame Days 2019, Åbo, Finland, August 28 - 29, 2019
Available from: 2019-09-27 Created: 2019-09-27 Last updated: 2019-10-03Bibliographically approved
Strandberg, A., Skoglund, N., Thyrel, M., Lestander, T. A., Broström, M. & Backman, R. (2019). Time-Resolved Study of Silicate Slag Formation During Combustion of Wheat Straw Pellets. Energy & Fuels, 33(3), 2308-2318
Open this publication in new window or tab >>Time-Resolved Study of Silicate Slag Formation During Combustion of Wheat Straw Pellets
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2019 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 33, no 3, p. 2308-2318Article in journal (Refereed) Published
Abstract [en]

Ash formation during single-fuel pellet combustion of wheat straw at 700 and 1000 °C was studied throughout fuel conversion by quench cooling and analysis at different char conversion degrees. The combination of X-ray microtomography analysis and scanning electronic microscopy with energy-dispersive X-ray spectroscopy showed that ash accumulated in rigid net structures at 700 °C with streaks or small beads surrounding the char, and the pellet mostly maintained its size during the entire fuel conversion. At 1000 °C, the ash formed high-density melts that developed into bubbles on the surface. As the conversion proceeded, these bubbles grew in size and covered parts of the active char surface area, but without entirely blocking the gas transport. The successive char conversion dissolved increasing amounts of calcium in the potassium silicate melts, probably causing differences in the release of potassium to the gas phase. Similarities were found with slag from a combustion experiment in a domestic boiler, with regard to relative composition and estimated and apparent viscosity of the slag. Complete char encapsulation by ash layers limiting char burnout was not found at the single pellet level, nor to any greater extent from the experiment performed in a small domestic boiler.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
National Category
Inorganic Chemistry Other Environmental Engineering
Identifiers
urn:nbn:se:umu:diva-157725 (URN)10.1021/acs.energyfuels.8b04294 (DOI)000462260600064 ()
Projects
Bio4Energy
Funder
Swedish Research Council, 2014-5041Bio4Energy
Available from: 2019-04-02 Created: 2019-04-02 Last updated: 2019-08-30Bibliographically approved
Hedayati, A., Lindgren, R., Boman, C., Skoglund, N. & Öhman, M. (2018). Ash transformation during single-pellet combustion of agricultural biomass fuels – focus on K and P. In: : . Paper presented at 27th international conference of Impacts of Fuel Quality on Power Production and the Environment, 23–28 September, 2018, Lake Louise, Canada.
Open this publication in new window or tab >>Ash transformation during single-pellet combustion of agricultural biomass fuels – focus on K and P
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2018 (English)Conference paper, Oral presentation with published abstract (Refereed)
National Category
Energy Engineering Other Chemistry Topics
Identifiers
urn:nbn:se:umu:diva-157284 (URN)
Conference
27th international conference of Impacts of Fuel Quality on Power Production and the Environment, 23–28 September, 2018, Lake Louise, Canada
Funder
Swedish Energy Agency, 41877-1
Available from: 2019-03-13 Created: 2019-03-13 Last updated: 2019-03-18
Strandberg, A., Thyrel, M., Skoglund, N., Lestander, T. A., Broström, M. & Backman, R. (2018). Biomass pellet combustion: cavities and ash formation characterized by synchrotron X-ray micro-tomography. Fuel processing technology, 176, 211-220
Open this publication in new window or tab >>Biomass pellet combustion: cavities and ash formation characterized by synchrotron X-ray micro-tomography
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2018 (English)In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 176, p. 211-220Article in journal (Refereed) Published
Abstract [en]

Ash formation during thermochemical conversion of biomass-based pellets influences both char conversion rates and ash-related operational problems. The objective of the present study was to provide detailed insights into changes in fuel and ash properties during fuel conversion. Pellets of poplar wood and wheat straw were used as model biofuels, representing vastly different compositions of ash-forming elements. Pellet samples at different char conversion phases were analyzed by synchrotron-based 3D X-ray micro-tomography, to map and visualize the development of cracks, internal cavities, and ash layers during conversion. The analysis of ash layers was complemented by scanning electron microscopy combined with energy-dispersive X-ray spectroscopy. The results provide new insights into how large cracks and internal cavities are developed already during devolatilization, for example, the poplar wood pellets had a 64% void fraction after the devolatilization stage. As expected, there were large variations between the ash layer properties for the two fuels. A porous, low density, and calcium-rich ash was formed from the poplar fuel, whereas the wheat straw ash was a high-density silicate melt that developed into bubbles on the surface. As the conversion proceeded, the wheat straw ash covered parts of the active char surface area, but without blocking the gas transport.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
ash composition, pellet, thermochemical conversion, wheat straw, poplar, SEM-EDS
National Category
Chemical Process Engineering Bioenergy
Identifiers
urn:nbn:se:umu:diva-146673 (URN)10.1016/j.fuproc.2018.03.023 (DOI)
Projects
Bio4Energy
Available from: 2018-04-17 Created: 2018-04-17 Last updated: 2019-09-02Bibliographically approved
Bozaghian, M., Rebbling, A., Larsson, S. H., Thyrel, M., Xiong, S. & Skoglund, N. (2018). Combustion characteristics of straw stored with CaCO3 in bubbling fluidized bed using quartz and olivine as bed materials. Applied Energy, 212, 1400-1408
Open this publication in new window or tab >>Combustion characteristics of straw stored with CaCO3 in bubbling fluidized bed using quartz and olivine as bed materials
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2018 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 212, p. 1400-1408Article in journal (Refereed) Published
Abstract [en]

The addition of Ca-containing compounds can reduce mass loss from agricultural biomass during storage. The resulting alkaline environment is detrimental to microorganisms present in the material. Theoretical analysis of Ca-containing biomass suggests that combustion properties are improved with respect to slagging. To validate the theoretical calculations, barley straw was utilized as a typical model agricultural biomass and combustion characteristics of straw pre-treated with 2 and 4 w/w% CaCO3 for combined improvement of storage and combustion properties were determined through combustion at 700 degrees C in a bench-scale bubbling fluidized-bed reactor (5 kW) using quartz and olivine sand as bed materials. The combustion characteristics were determined in terms of elemental composition and compound identification in bed ash and bed material including agglomerates, fly ash, particulate matter as well as flue gas measurements. The addition of CaCO3 to straw had both positive and negative effects on its combustion characteristics. Both additive levels raised the total de fluidization temperature for both quartz and olivine, and olivine proved to be less susceptible than quartz to reactions with alkali. With Ca-additives, the composition of deposits and fine particulate matter changed to include higher amounts of KCl potentially leading to higher risk for alkali chloride-induced corrosion. Flue gas composition was heavily influenced by CaCO3 additives by significantly elevated CO concentrations likely related to increased levels of gaseous alkali compounds. The results suggest that it is necessary to reduce gaseous alkali compounds, e.g. through kaolin or sulphur addition, if alkali-rich straw is to be co-combusted with Ca-rich biomass or large amounts of Ca-additives.

Keywords
Agricultural biomass, Barley straw, Calcium additive, Biomass storage, Fluidized bed combustion, Ash emistry
National Category
Energy Engineering
Identifiers
urn:nbn:se:umu:diva-145589 (URN)10.1016/j.apenergy.2017.12.112 (DOI)000425200700103 ()
Projects
Bio4Energy
Available from: 2018-03-20 Created: 2018-03-20 Last updated: 2019-09-02Bibliographically approved
Sepman, A., Jansson, K., Skoglund, N. & Wiinikka, H. (2018). Combustion characterization of five recyclable metal fuels. In: : . Paper presented at 37th International symposium on combustion, 29 July - 3 August, 2018, Dublin, Ireland.
Open this publication in new window or tab >>Combustion characterization of five recyclable metal fuels
2018 (English)Conference paper, Poster (with or without abstract) (Refereed)
National Category
Energy Engineering
Identifiers
urn:nbn:se:umu:diva-157285 (URN)
Conference
37th International symposium on combustion, 29 July - 3 August, 2018, Dublin, Ireland
Available from: 2019-03-13 Created: 2019-03-13 Last updated: 2019-03-18
Projects
Fundamental studies of chemical speciation in ash fractions from thermal conversion of biomass and waste streams focusing on phosphates and heavy metals [2017-05331_VR]; Umeå University
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-5777-9241

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