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Fagerström, Jonathan
Publications (10 of 11) Show all publications
Fagerström, J., Steinvall, E., Boström, D. & Boman, C. (2016). Alkali transformation during single pellet combustion of soft wood and wheat straw. Fuel processing technology, 143, 204-212
Open this publication in new window or tab >>Alkali transformation during single pellet combustion of soft wood and wheat straw
2016 (English)In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 143, p. 204-212Article in journal (Refereed) Published
Abstract [en]

Controlling slag and deposit formation during thermochemical fuel conversion requires a fundamental understanding about ash transformation. In this work, a macro-TGA reactor was used to determine the release of ash forming elements during devolatilization and char combustion of single pellets. Soft wood and wheat straw were combusted at two temperatures (700 °C and 1000 °C) and the residual ashes were collected and analyzed for morphology, elemental and phase composition. The results showed that the single pellet combustion exhibit similar release character as in grate boilers. The temporal release was found to be both temperature and fuel dependent. For wood, the release of potassium occurred mostly during char combustion regardless of furnace temperature. Similar results were found for straw at 700 °C, but the temperature increase to 1000 °C implied that the release occurred already during devolatilization. The differences are presumably explained by different fuel phase compositions. The residual ash were composed of three different categories of phases; crystalline compounds, molten ash (glass) and char, and the work concludes that K was captured by crystalline K/Ca-carbonates as well as in amorphous glassy silicates for wood, and by almost fully molten ash of glassy silicates for straw. The fuel conversion processes occurring on a grate influence the fuel combustibility in terms of e.g. burnout, slag formation and release of fine particle and deposit forming matter, and the present work has given novel insights into the specific alkali behavior during biomass fuel conversion.

Keywords
Biomass, Combustion, Ash, Alkali, Release, Single pellet
National Category
Physical Sciences
Identifiers
urn:nbn:se:umu:diva-102732 (URN)10.1016/j.fuproc.2015.11.016 (DOI)000369455300023 ()
Projects
Bio4Energy
Available from: 2015-05-04 Created: 2015-05-04 Last updated: 2019-09-02Bibliographically approved
Fagerström, J., Rebbling, A., Olwa, J., Steinvall, E., Boström, D., Öhman, M. & Boman, C. (2015). Control strategies for reduction of alkali release during grate combustion of woody biomass: influence of process parameters and fuel additives. Fuel processing technology
Open this publication in new window or tab >>Control strategies for reduction of alkali release during grate combustion of woody biomass: influence of process parameters and fuel additives
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2015 (English)In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188Article in journal (Refereed) Accepted
National Category
Physical Sciences
Identifiers
urn:nbn:se:umu:diva-102735 (URN)
Available from: 2015-05-04 Created: 2015-05-04 Last updated: 2019-01-15
Fagerström, J. (2015). Fine particle emissions and slag formation in fixed-bed biomass combustion: aspects of fuel engineering. (Doctoral dissertation). Umeå: Umeå Universitet
Open this publication in new window or tab >>Fine particle emissions and slag formation in fixed-bed biomass combustion: aspects of fuel engineering
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

There is a consensus worldwide that the share of renewable energy sources should be increased to mitigate climate change. The strive to increase the renewable energy fraction can partly be met by an increased utilization of different biomass feedstocks. Many of the "new" feedstocks puts stress on certain challenges such as air pollution emissions and operation stability of the combustion process. The overall objective was to investigate, evaluate, and explain the effects of fuel design and combustion control - fuel engineering - as primary measures for control of slag formation, deposit formation, and fine particle emissions during biomass combustion in small and medium scale fixed-bed appliances. The work in this thesis can be outlined as having two main focus areas, one more applied regarding fuel engineering measures and one more fundamental regarding the time-resolved release of ash forming elements, with particular focus on potassium.

The overall conclusion related to the abatement of particle emissions and slag formation, is that the release of fine particle and deposit forming matter can be controlled simultaneously as the slag formation during fixed-bed biomass combustion. The methodology is in this perspective denoted “fuel engineering” and is based on a combined approach including both fuel design and process control measures. The studies on time-resolved potassium release showed that a Macro-TG reactor with single pellet experiments was a valuable tool for studying ash transformation along the fuel conversion. The combination of dedicated release determinations based on accurate mass balance considerations and ICP analysis, with phase composition characterization by XRD, is important for the understanding of potassium release in general and time-resolved data in particular. For wood, the results presented in this work supports the potassium release mechanism from "char-K" but questions the previously suggested release mechanism from decomposition of K-carbonates. For straw, the present data support the idea that the major part of the potassium release is attributed to volatilization of KCl. To further explore the detailed mechanisms, the novel approach developed and applied in this work should be complemented with other experimental and analytical techniques.

The research in this thesis has explored some of the challenges related to the combined phenomena of fuel conversion and ash transformation during thermochemical conversion of biomass, and has contributed with novel methods and approaches that have gained new knowledge to be used for the development of more effective bioenergy systems.

Place, publisher, year, edition, pages
Umeå: Umeå Universitet, 2015. p. 73
Keywords
Renewable energy, biomass, thermochemical fuel conversion, combustion, fine particle emissions, slag formation, fixed-bed, ash chemistry, fuel engineering, release
National Category
Chemical Process Engineering Energy Engineering Environmental Engineering
Identifiers
urn:nbn:se:umu:diva-102687 (URN)978-91-7601-274-1 (ISBN)
Public defence
2015-05-25, KBC-huset, sal KB3A9, Umeå Universitet, Umeå, 13:00 (Swedish)
Opponent
Supervisors
Available from: 2015-05-04 Created: 2015-04-30 Last updated: 2018-06-07Bibliographically approved
Näzelius, I.-L., Fagerström, J., Boman, C., Boström, D. & Öhman, M. (2015). Slagging in fixed-bed combustion of phosphorus-poor biomass: critical ash-forming processes and compositions. Energy & Fuels, 29(2), 894-908
Open this publication in new window or tab >>Slagging in fixed-bed combustion of phosphorus-poor biomass: critical ash-forming processes and compositions
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2015 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 29, no 2, p. 894-908Article in journal (Refereed) Published
Abstract [en]

Slagging in combustion facilities is not welcomed, because it may cause technical and operational problems, as well as extra costs. Increased understanding of the critical slagging subprocesses makes it easier to suggest semiempirical models and fuel indexes for predicting the slagging tendencies of different fuels. That could open the biomass market for potentially more troublesome raw materials. The objective of this work was to determine critical ash-forming processes and compositions in the fixed-bed combustion of phosphorus-poor biomass fuels. This was achieved by performing a systematic review of data and experience gathered from combustion experiments in a small grate burner of 36 different biomasses, as well as chemical analysis of their bottom ashes and slags. The paper presents a discussion of the slagging tendency in phosphorus-poor biomass by combining three different slagging classifications, culminating in a proposed starting point for a new slagging index. The slag (ash particles >3.15 mm in size) formed during the combustion experiments has been described according to the fraction of fuel ash that forms slag (expressed in terms of weight percent), the visual sintering category (1-4), and the viscosity predictions. The results explain that both the fraction of melt and its viscosity are critical for the slag formation process in phosphorus-poor biomasses. In addition, fuels with low Si/K ratio along with a higher Ca concentration may form a low viscous carbonate melt that is not prone to form slag. Increased Si and lowered Ca concentration will increase the amount of formed silicate melt formed, as well as its viscosity, thus resulting in a more sticky melt.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2015
National Category
Energy Engineering Chemical Engineering
Identifiers
urn:nbn:se:umu:diva-101613 (URN)10.1021/ef502531m (DOI)000349943300050 ()
Available from: 2015-04-10 Created: 2015-04-07 Last updated: 2018-06-07Bibliographically approved
Fagerström, J., Näzelius, I.-L., Gilbe, C., Boström, D., Öhman, M. & Boman, C. (2014). Influence of Peat Ash Composition on Particle Emissions and Slag Formation in Biomass Grate Co-combustion. Energy & Fuels, 28(5), 3403-3411
Open this publication in new window or tab >>Influence of Peat Ash Composition on Particle Emissions and Slag Formation in Biomass Grate Co-combustion
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2014 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 28, no 5, p. 3403-3411Article in journal (Refereed) Published
Abstract [en]

Co-combustion by fuel blending of peat and biomass has shown positive effects on operational problems. However, peat ash compositions vary considerably, and this has been shown to affect the potential for operational problems in different fuel-blending situations. The present work used three different peat types with the objective to elucidate how the variation in peat ash composition influences both particle emissions and slag formation during co-combustion with three different biomasses in a small-scale pellet boiler. Estimations of potassium release and slag formation were performed and discussed in relation to fuel composition in the (K2O + Na2O) (CaO + MgO) (SiO2) system. All tested peat types reduced the fine particle emissions by capturing potassium into the bottom ash as one or several of the following forms: slag, sulfates, chlorides, and alumina silicates. However, there were considerable differences between the peat types, presumably depending upon both their content and mineral composition of silicon, calcium, aluminum, and sulfur. Some general important and beneficial properties of peat type in co-combustion situations with biomass are defined here, but the specific blending proportion of peat should be decided on an individual basis for each scenario based on the relative contents in the fuel mixture of the most relevant ash-forming elements.

National Category
Bio Materials
Identifiers
urn:nbn:se:umu:diva-90439 (URN)10.1021/ef4023543 (DOI)000336199300063 ()
Available from: 2014-07-09 Created: 2014-06-23 Last updated: 2018-06-07Bibliographically approved
Qu, Z., Fagerström, J., Steinvall, E., Broström, M., Boman, C. & Florian, S. (2014). Real-time In-Situ Detection of Potassium Release during Combustion of Pelletized Biomass using Tunable Diode Laser Absorption Spectroscopy. In: Impacts of Fuel Quality on Power Production October 26 –31, 2014, Snowbird, Utah, USA: . Paper presented at Impacts of Fuel Quality on Power Production October 26 –31, 2014 Snowbird Resort & Conference Center Snowbird, Utah (pp. 1-14).
Open this publication in new window or tab >>Real-time In-Situ Detection of Potassium Release during Combustion of Pelletized Biomass using Tunable Diode Laser Absorption Spectroscopy
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2014 (English)In: Impacts of Fuel Quality on Power Production October 26 –31, 2014, Snowbird, Utah, USA, 2014, p. 1-14Conference paper, Published paper (Other academic)
Abstract [en]

Tunable diode laser absorption spectroscopy (TDLAS) was used for quantitative in-situ detection of gaseous elemental potassium (K) at distances 2-11 mm above biomass pellets combusted in a macro-thermogravimetric analyzer (macro-TGA). Single pellets of energy wood (EW) and wheat straw (WS) were converted in air at a furnace temperature of 850 °C and a carrier flow rate of 15 liters per minute. A second TDLAS system measured water vapor concentration and temperature above the pellets. In addition, semi-time-resolved K release data was obtained from conventional ICP-MS/AES analysis of fuel/ash residues collected at several occasions during devolatilization and char combustion. It was found that the fuels differ with respect to relative K-release and temporal release histories. Significant concentrations of K(g) were detected with TDLAS above the pellets during devolatilization, but no K(g) was observed during char combustion, independent of the fuel type. The amount of K(g)tot measured above the pellets during devolatilization was larger for EW than for WS, even though the total K content of WS was a factor of 60 higher. By combining TDLAS and ICP data, and supported by equilibrium calculations, these results indicate that, during devocalization, K is mainly released as KCl from wheat straw, whereas both KCl and KOH are released from energy wood.

National Category
Chemical Process Engineering
Identifiers
urn:nbn:se:umu:diva-95732 (URN)
Conference
Impacts of Fuel Quality on Power Production October 26 –31, 2014 Snowbird Resort & Conference Center Snowbird, Utah
Available from: 2014-11-04 Created: 2014-11-04 Last updated: 2018-06-07Bibliographically approved
Westerlund, L., Hermansson, R. & Fagerström, J. (2012). Flue gas purification and heat recovery: A biomass fired boiler supplied with an open absorption system. Applied Energy, 96, 444-450
Open this publication in new window or tab >>Flue gas purification and heat recovery: A biomass fired boiler supplied with an open absorption system
2012 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 96, p. 444-450Article in journal (Refereed) Published
Abstract [en]

A new technique for energy recovery combined with particle separation from flue gas has been tested in this project. A conventional small boiler for biofuel produces besides heat also particles to the environment through the flue gas. Decreasing the impact on the environment is desirable. Increased efficiency can be obtained if the temperature and water content of the flue gas can be further reduced. Installing an open absorption system in the heat production unit fulfils both these demands. An experimental unit has been built and tested in the last 2 years. The results show a reduction of particles in the flue gas by 33-44% compared to the ordinary system. At the same time the heat production from the unit increased by 40% when fired with wet biofuels. (C) 2012 Elsevier Ltd. All rights reserved.

Keywords
Open absorption system, Particle reduction, Heat recovery
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-57424 (URN)10.1016/j.apenergy.2012.02.085 (DOI)000305595500045 ()
Available from: 2012-07-23 Created: 2012-07-23 Last updated: 2018-06-08Bibliographically approved
Fagerström, J., Nyström, R., Broström, M., Dan, B. & Boman, C. (2011). Fuel conversion of large samples in a thermogravimetric analyzer set-up: method description and applications. In: 19th European Biomass Conference and Exhibition: From Research to Industry and Markets. Paper presented at 19th European Biomass Conference and Exhibition, Berlin, Germany, June 6-10, 2011.
Open this publication in new window or tab >>Fuel conversion of large samples in a thermogravimetric analyzer set-up: method description and applications
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2011 (English)In: 19th European Biomass Conference and Exhibition: From Research to Industry and Markets, 2011Conference paper, Oral presentation with published abstract (Refereed)
National Category
Chemical Process Engineering
Identifiers
urn:nbn:se:umu:diva-86585 (URN)
Conference
19th European Biomass Conference and Exhibition, Berlin, Germany, June 6-10, 2011
Available from: 2014-03-02 Created: 2014-03-02 Last updated: 2018-06-08
Rönnbäck, M., Gustavsson, L., Hermansson, S., Skoglund, N., Fagerström, J., Boman, C., . . . Öhman, M. (2011). Förbränningskaraktärisering och förbränningsteknisk utvärdering av olika pelletsbränslen - syntes av projektet. Borås: SP Sveriges Tekniska Forskningsinstitut
Open this publication in new window or tab >>Förbränningskaraktärisering och förbränningsteknisk utvärdering av olika pelletsbränslen - syntes av projektet
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2011 (Swedish)Report (Other academic)
Place, publisher, year, edition, pages
Borås: SP Sveriges Tekniska Forskningsinstitut, 2011. p. 258
Series
SP Rapport, ISSN 0284-5172 ; 2011:40
National Category
Natural Sciences Chemical Engineering
Identifiers
urn:nbn:se:umu:diva-60958 (URN)978-91-86622-70-1 (ISBN)
Available from: 2012-11-07 Created: 2012-11-05 Last updated: 2018-06-08Bibliographically approved
Fagerström, J., Boström, D. & Boman, C.Influence of kaolin additive on the release of ash forming elements during biomass combustion.
Open this publication in new window or tab >>Influence of kaolin additive on the release of ash forming elements during biomass combustion
(English)Manuscript (preprint) (Other academic)
National Category
Physical Sciences
Identifiers
urn:nbn:se:umu:diva-102733 (URN)
Available from: 2015-05-04 Created: 2015-05-04 Last updated: 2018-06-07
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