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Boman, Christoffer
Publications (10 of 91) Show all publications
Rebbling, A., Sundberg, P., Fagerström, J., Carlborg, M., Tullin, C., Boström, D., . . . Skoglund, N. (2020). Demonstrating Fuel Design To Reduce Particulate Emissions and Control Slagging in Industrial-Scale Grate Combustion of Woody Biomass. Energy & Fuels, 34(2), 2574-2583
Open this publication in new window or tab >>Demonstrating Fuel Design To Reduce Particulate Emissions and Control Slagging in Industrial-Scale Grate Combustion of Woody Biomass
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2020 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 34, no 2, p. 2574-2583Article in journal (Refereed) Published
Abstract [en]

The demand for increased overall efficiency, improved fuel flexibility, and more stringent environmental legislations promotes the development of new fuel- and technology-related concepts for the bioenergy sector. Previous research has shown that careful consideration of the fuel ash composition and the adjustment of the same via various routes, i.e., fuel design, have the potential to alter the ash transformation reactions, leading to, e.g., a reduction of the formation of slag or entrained inorganic ash particles. The objective of the present work was, therefore, to demonstrate the use of fuel design as a primary measure to reduce the emission of PM1 during combustion of woody biomass in medium-scale grate-fired boilers while keeping the slag formation at a manageable level. This was achieved by designing fuel blends of woody biomass with carefully selected Scandinavian peats rich in Si, Ca, and S. The work includes results from three experimental campaigns, performed in three separate grate-fired boilers of different sizes, specifically 0.2 MWth, 2 MWth, and 4 MWth. In one of the campaigns, softwood-based stemwood pellets were copelletized with different additions of peat (5 and 15 wt %) before combustion. In the other campaigns, peat was added in a separate fuel feed to Salix chips (15 wt % peat) and softwood-based stemwood pellets (10 and 20 wt % peat). Particulate matter and bottom ashes were characterized by scanning electron microscopy-energy-dispersive X-ray spectroscopy for morphology and elemental composition as well as by powder X-ray diffraction for crystalline phase composition. The results show that the fuel design approach provided PM1 reduction for all fuel blends between 30 and 50%. The PM1 reduction could be achieved without causing operational problems due to slagging for any of the three commercial boilers used, although an expected increased slagging tendency was observed. Overall, this paper illustrates that fuel design can be implemented on an industrial scale by achieving the desired ash transformation reactions, in this case, leading to a reduction of fine particulate emissions by up to 50% without any operational disturbances due to slag formation on the grate.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2020
Keywords
Redox reactions, Reaction products, Biomass, Fuels, Particulate matter
National Category
Energy Engineering
Identifiers
urn:nbn:se:umu:diva-169362 (URN)10.1021/acs.energyfuels.9b03935 (DOI)000518215400147 ()
Available from: 2020-04-07 Created: 2020-04-07 Last updated: 2020-04-07Bibliographically approved
Carvalho, R. L., Yadav, P., García-López, N., Lindgren, R., Nyberg, G., Diaz-Chavez, R., . . . Athanassiadis, D. (2020). Environmental Sustainability of Bioenergy Strategies in Western Kenya to Address Household Air Pollution. Energies, 13(3), Article ID 719.
Open this publication in new window or tab >>Environmental Sustainability of Bioenergy Strategies in Western Kenya to Address Household Air Pollution
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2020 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 13, no 3, article id 719Article in journal (Refereed) Published
Abstract [en]

Over 640 million people in Africa are expected to rely on solid-fuels for cooking by 2040. In Western Kenya, cooking inefficiently persists as a major cause of burden of disease due to household air pollution. Efficient biomass cooking is a local-based renewable energy solution to address this issue. The Life-Cycle Assessment tool Simapro 8.5 is applied for analyzing the environmental impact of four biomass cooking strategies for the Kisumu County, with analysis based on a previous energy modelling study, and literature and background data from the Ecoinvent and Agrifootprint databases applied to the region. A Business-As-Usual scenario (BAU) considers the trends in energy use until 2035. Transition scenarios to Improved Cookstoves (ICS), Pellet-fired Gasifier Stoves (PGS) and Biogas Stoves (BGS) consider the transition to wood-logs, biomass pellets and biogas, respectively. An Integrated (INT) scenario evaluates a mix of the ICS, PGS and BGS. In the BGS, the available biomass waste is sufficient to be upcycled and fulfill cooking demands by 2035. This scenario has the lowest impact on all impact categories analyzed followed by the PGS and INT. Further work should address a detailed socio-economic analysis of the analyzed scenarios.

Place, publisher, year, edition, pages
MDPI, 2020
Keywords
agroforestry, waste valorization, sustainable development goals, renewable energy, bioenergy transitions, circular bioeconomy, clean cooking, life-cycle assessment, energy policy
National Category
Bioenergy
Identifiers
urn:nbn:se:umu:diva-170012 (URN)10.3390/en13030719 (DOI)000522489000212 ()
Available from: 2020-05-05 Created: 2020-05-05 Last updated: 2020-05-05Bibliographically approved
Korhonen, K., Kristensen, T. B., Falk, J., Lindgren, R., Andersen, C., Carvalho, R. L., . . . Virtanen, A. (2020). Ice-nucleating ability of particulate emissions from solid-biomass-fired cookstoves: an experimental study. Atmospheric Chemistry And Physics, 20(8), 4951-4968
Open this publication in new window or tab >>Ice-nucleating ability of particulate emissions from solid-biomass-fired cookstoves: an experimental study
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2020 (English)In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 20, no 8, p. 4951-4968Article in journal (Refereed) Published
Abstract [en]

This research was part of the Salutary Umea Study of Aerosols in Biomass Cookstove Emissions (SUSTAINE) laboratory experiment campaign. We studied ice-nucleating abilities of particulate emissions from solid-fuel-burning cookstoves, using a portable ice nuclei counter, Spectrometer Ice Nuclei (SPIN). These emissions were generated from two traditional cookstove types commonly used for household cooking in sub-Saharan Africa and two advanced gasifier stoves under research to promote sustainable development alternatives. The solid fuels studied included biomass from two different African tree species, Swedish softwood and agricultural residue products relevant to the region. Measurements were performed with a modified version of the standard water boiling test on polydisperse samples from flue gas during burning and size-selected accumulation mode soot particles from a 15 m(3) aerosol-storage chamber. The studied soot particle sizes in nanometers were 250, 260, 300, 350, 400, 450 and 500. From this chamber, the particles were introduced to water-supersaturated freezing conditions (-32 to -43 degrees) in the SPIN. Accumulation mode soot particles generally produced an ice-activated fraction of 10 3 in temperatures 1-1.5 degrees C higher than that required for homogeneous freezing at fixed RHw = 115 %. In five special experiments, the combustion performance of one cookstove was intentionally modified. Two of these exhibited a significant increase in the ice-nucleating ability of the particles, resulting in a 10(3) ice activation at temperatures up to 5.9 degrees C higher than homogeneous freezing and the observed increased ice-nucleating ability. We investigated six different physico-chemical properties of the emission particles but found no clear correlation between them and increasing ice-nucleating ability. We conclude that the freshly emitted combustion aerosols form ice via immersion and condensation freezing at temperatures only moderately above homogeneous freezing conditions.

Place, publisher, year, edition, pages
Nicolaus Copernicus University Press, 2020
National Category
Meteorology and Atmospheric Sciences
Identifiers
urn:nbn:se:umu:diva-170825 (URN)10.5194/acp-20-4951-2020 (DOI)000529394700004 ()
Funder
Swedish Research Council Formas, 942-2015-1385Swedish Research Council Formas, 2015-992Swedish Research Council Formas, 2013-01023Swedish Research Council, 2017-05016Swedish Research Council, 2018-04200Swedish Research Council, 2013-05021The Kempe Foundations, JCK-1516
Available from: 2020-05-25 Created: 2020-05-25 Last updated: 2020-05-25Bibliographically approved
Strandberg, A., Carlborg, M., Boman, C. & Broström, M. (2019). Ash Transformation During Single-Pellet Combustion of a Silicon-Poor Woody Biomass. Energy & Fuels, 33(8), 7770-7777
Open this publication in new window or tab >>Ash Transformation During Single-Pellet Combustion of a Silicon-Poor Woody Biomass
2019 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 33, no 8, p. 7770-7777Article in journal (Refereed) Published
Abstract [en]

Biomass fuels with calcium and potassium as the main ash-forming elements are expected to form ash consisting mainly of carbonates and oxides. These carbonates are stable in a rather narrow temperature range, which in turn depends on the Ca/K ratio, as well as on the surrounding atmosphere. The objective of the present study was to perform a detailed characterization of ash formation and transformation at a single-pellet level during combustion of silicon-poor woody biomass fuel. Combustion tests were performed with poplar in a single-pellet isothermal thermogravimetric analyzer operated at different temperatures and atmospheres and quenched at different stages of fuel conversion. The char and residual ashes were characterized for morphology and chemical composition. The focus of the experimental work in this study was on the time (conversion) resolved ash formation and transformations at the late part of the char combustion phase. Thermodynamic equilibrium calculations were used both to design the experiments and to support the interpretation of experimental results. It was concluded that carbonates were, in general, stable at low temperatures (here, 600–800 °C), identified as CaCO3, K2Ca2(CO3)3, and K2Ca(CO3)2, and decomposed at higher temperatures. In addition, a combined carbonate and phosphate phase in the form of carbonate apatite, Ca9.9(PO4)6(CO3)0.9, was also found, mainly at lower temperatures. However, for char/ash samples quenched before full conversion, CaCO3 was still found at temperatures higher than expected, possibly explained by the stabilizing effect of locally higher CO2 partial pressure within the burning fuel particles. Thus, the results of the present study provide new insights into conversion-based ash formation and transformation in a burning fuel particle with relevance for combustion of Si-poor woody biomass fuels.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
National Category
Bioenergy
Identifiers
urn:nbn:se:umu:diva-163274 (URN)10.1021/acs.energyfuels.9b00937 (DOI)000481569100090 ()2-s2.0-85070870382 (Scopus ID)
Available from: 2019-09-12 Created: 2019-09-12 Last updated: 2019-09-16Bibliographically approved
Pourazar, J., Sehlstedt, M., Rankin, G., Uski, O., Boman, C., Lopez, N., . . . Muala, A. (2019). Exposure to wood smoke induced activation of lymphocyte subtypes in peripheral blood. Paper presented at European-Respiratory-Society (ERS) International Congress, Madrid, SPAIN, SEP 28-OCT 02, 2019.. European Respiratory Journal, 54
Open this publication in new window or tab >>Exposure to wood smoke induced activation of lymphocyte subtypes in peripheral blood
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2019 (English)In: European Respiratory Journal, ISSN 0903-1936, E-ISSN 1399-3003, Vol. 54Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
Sheffield: European Respiratory Society Journals, 2019
Keywords
Air pollution, Systemic effect, Inflammation
National Category
Respiratory Medicine and Allergy
Identifiers
urn:nbn:se:umu:diva-168164 (URN)10.1183/13993003.congress-2019.PA1983 (DOI)000507372402143 ()
Conference
European-Respiratory-Society (ERS) International Congress, Madrid, SPAIN, SEP 28-OCT 02, 2019.
Note

Supplement: 63. Meeting Abstract: PA1983.

Available from: 2020-03-17 Created: 2020-03-17 Last updated: 2020-03-17Bibliographically approved
Sandström, K., Boman, C., Weidemann, E. & Broström, M. (2019). Fluorine reactions in MSW combustion. In: European Biomass Conference and Exhibition: 2019. Paper presented at EUBCE 2019, 27th European Biomass Conference & Exhibition, Lisbon, Portugal, May 27-30, 2019.
Open this publication in new window or tab >>Fluorine reactions in MSW combustion
2019 (English)In: European Biomass Conference and Exhibition: 2019, 2019Conference paper, Published paper (Refereed)
Abstract [en]

Fluorine is of increasing concern in waste combustion since fluorinated plastics constitute anincreasing share of waste fractions entering CHP plants. Alkali fluorides could potentially causesimilar problems as are well known for the corresponding chlorides. However, there are somefundamental differences in thermodynamic stabilities. Available literature essentially lacks theexperimental evidence needed to draw any further conclusions on the extent of any fluorine relatedproblems, but recently a MSW fired CHP reported alarming deposit growth rates, possibly relatedto a delivery of fluorine containing fuels. The objective of the present study was to experimentallyevaluate some of the thermodynamic considerations mentioned. Fuels were prepared by addingNaCl, NaF and S to softwood pellets. Deposit and aerosol samples were analyzed with SEM-EDSand XRD, and evaluated together with fundamental thermodynamic phase equilibriumconsiderations to provide new and important information on the ash forming reactions and theirimplications. The results from the combustion tests showed that the fluorine found on the depositprobe was in form of NaF and Na3F (SO4) in qualitative agreement with thermodynamicequilibrium calculations.

National Category
Chemical Engineering
Identifiers
urn:nbn:se:umu:diva-171119 (URN)
Conference
EUBCE 2019, 27th European Biomass Conference & Exhibition, Lisbon, Portugal, May 27-30, 2019
Available from: 2020-05-27 Created: 2020-05-27 Last updated: 2020-05-28Bibliographically approved
Carvalho, R. L., Lindgren, R., Lopez, N., Nyambane, A., Nyberg, G., Diaz-Chavez, R. & Boman, C. (2019). Household air pollution mitigation with integrated biomass/cookstove strategies in Western Kenya. Energy Policy, 131, 168-186
Open this publication in new window or tab >>Household air pollution mitigation with integrated biomass/cookstove strategies in Western Kenya
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2019 (English)In: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 131, p. 168-186Article in journal (Refereed) Published
Abstract [en]

Traditional cooking is today's largest global environmental health risk. Over 640 million people in Africa are expected to rely on biomass for cooking by 2040. In Kenya, cooking inefficiently with wood and charcoal persists as a cause of deforestation and household air pollution. This research analyses the effects of four biomass cookstove strategies on reducing air pollutant emissions in Kisumu County between 2015 and 2035 using the Long-Range Energy Alternatives Planning system. The Business as Usual scenario (BAU) was developed considering the historical trends in household energy use. Energy transition scenarios to Improved Cookstoves (ICS), Pellet Gasifier Stoves (PGS) and Biogas Stoves (BGS) were applied to examine the impact of these systems on energy savings and air pollution mitigation. An integrated scenario (INT) was evaluated as a mix of the ICS, PGS and BGS. The highest energy savings, in relation to the BAU, are achieved in the BGS (30.9%), followed by the INT (23.5%), PGS (19.4%) and ICS (9.2%). The BGS offers the highest reduction in the GHG (37.6%), CH4 (94.3%), NMVOCs (85.0%), CO (97.4%), PM2.5 (64.7%) and BC (48.4%) emissions, and the PGS the highest reduction in the N2O (83.0%) and NOx (90.7%) emissions, in relation to the BAU.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Biomass pellets, Biogas, Cookstoves, Energy forecasting, Global warming, Local air pollutants
National Category
Energy Systems Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-161498 (URN)10.1016/j.enpol.2019.04.026 (DOI)000472125200015 ()
Projects
Bio4Energy
Funder
Swedish Research Council Formas, 942-2015-1385The Kempe Foundations, JCK-1516
Available from: 2019-07-12 Created: 2019-07-12 Last updated: 2019-09-02Bibliographically approved
Schön, C., Feldmeier, S., Hartmann, H., Schwabl, M., Dahl, J., Rathbauer, J., . . . Burval, J. (2019). New Experimental Evaluation Strategies Regarding Slag Prediction of Solid Biofuels in Pellet Boilers. Energy & Fuels, 33(11), 11985-11995
Open this publication in new window or tab >>New Experimental Evaluation Strategies Regarding Slag Prediction of Solid Biofuels in Pellet Boilers
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2019 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 33, no 11, p. 11985-11995Article in journal (Refereed) Published
Abstract [en]

Pellet boilers and pellet stoves are widely used for heat production. But in most cases, only specific wood pellets with a low ash content are approved due to the increased risk of slagging and limited deashing capacity. The ash fusion test (AFT), according to prCEN/TS 15370-1, is currently the only standard method for the prediction of slagging. This method is not feasible for all biomass fuel types, since sometimes the characteristic temperatures cannot be determined or the characteristic shapes do not occur for temperature determination. Furthermore, the method is costly and requires complex instrumental infrastructure. Hence, a demand for more expressive or more rapid methods to characterize slag formation potential of fuels is often claimed. Based on a literature study, four such laboratory test methods were chosen, partly adapted, and then experimentally investigated. These methods included thermal treatment of the fuel itself or the ashes of the fuel and were the rapid slag test, CIEMAT, the slag analyzer, and the newly developed pellet ash and slag sieving assessment (PASSA) method. Method performance was practically assessed using 14 different biomass fuel pellets, which were mainly from different assortments of wood, but also herbaceous or other nonwoody fuels. The results from the tests with these four alternative methods were evaluated by comparing to both results from standard AFT and results from full-scale combustion tests performed over a maximum of 24 h. Seven different pellet boilers were assessed, of which one boiler was used to apply all 14 test fuels. According to the granulometric ash analysis (i.e., the ratio of >1 mm-fraction toward total ash formed), the sensitivity of the new test methods to depict slagging phenomena at a suitable level of differentiation was assessed. Satisfactory conformity of the boiler ash assessment (reference) was found for both, the slag analyzer and the PASSA method. The latter may, in particular, be seen as a promising and relatively simple low-input procedure, which can provide more real-life oriented test results for fixed-bed combustion. The standardized AFT could, however, not sufficiently predict the degree of slag actually formed in the reference boiler, particularly when only wood fuels are regarded.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
National Category
Energy Engineering Renewable Bioenergy Research
Identifiers
urn:nbn:se:umu:diva-166837 (URN)10.1021/acs.energyfuels.9b03098 (DOI)000499741900153 ()
Available from: 2020-01-03 Created: 2020-01-03 Last updated: 2020-01-03Bibliographically approved
Rebbling, A., Fagerström, J., Steinvall, E., Carlborg, M., Öhman, M. & Boman, C. (2019). Reduction of Alkali Release by Two Fuel Additives at Different Bed Temperatures during Grate Combustion of Woody Biomass. Energy & Fuels, 33(11), 11041-11048
Open this publication in new window or tab >>Reduction of Alkali Release by Two Fuel Additives at Different Bed Temperatures during Grate Combustion of Woody Biomass
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2019 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 33, no 11, p. 11041-11048Article in journal (Refereed) Published
Abstract [en]

The use of small- and medium-scale combustion of biomass for energy utilization is expected to grow in the coming decades. To meet standards and legislation regarding particle emissions and to reduce corrosion and deposit formation, it is crucial to reduce the release of alkali species from the fuel. This can be achieved by capturing the volatile alkali in the residual bottom ash as more thermally stable compounds. In this work, we investigate the combination of primary measures, i.e., process parameters and fuel additives, for reduction of the release of K and Na from the fuel bed during fixed bed combustion. In addition, the influence of these combined measures on fine particle emissions was explored. The results showed a clear influence of the process parameters, herein bed temperature, and that a significant reduction of the alkali release and PM1 emissions can be achieved by correct settings. Furthermore, the application of additives (kaolin and diammonium sulfate) reduced both K and Na release even further. The observed effects on the release behavior was mainly explained by the formation of KAlSiO4 and K2SO4 during addition of kaolin and diammonium sulfate, respectively. This work therefore emphasizes the importance of good control over the fuel bed conditions, especially temperature, when these additives are applied. To reduce the potential deactivation (for kaolinite) and melting (for K2SO4), the control of bed temperature is vital. Thus, it was concluded that the release of volatile alkali species and related fine particle emissions in small- and medium-scale biomass heat and power plants using wood fuels could be significantly reduced by a correct combination of controlling the combustion parameters and the use of fuel additives.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
National Category
Chemical Process Engineering Energy Systems
Identifiers
urn:nbn:se:umu:diva-165214 (URN)10.1021/acs.energyfuels.9b02391 (DOI)000499741900061 ()
Funder
Swedish Energy AgencyBio4Energy
Available from: 2019-11-15 Created: 2019-11-15 Last updated: 2020-01-03Bibliographically approved
Muala, A., Österdahl, R., Sehlstedt, M., Rankin, G., Pourazar, J., Bosson, J. A., . . . Öhberg, F. (2019). Small airways effects of exposure to wood smoke. Paper presented at European-Respiratory-Society (ERS) International Congress, Madrid, SPAIN, SEP 28-OCT 02, 2019.. European Respiratory Journal, 54
Open this publication in new window or tab >>Small airways effects of exposure to wood smoke
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2019 (English)In: European Respiratory Journal, ISSN 0903-1936, E-ISSN 1399-3003, Vol. 54Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
Sheffield: European Respiratory Society Journals, 2019
Keywords
Asthma, Air pollution
National Category
Respiratory Medicine and Allergy
Identifiers
urn:nbn:se:umu:diva-168166 (URN)10.1183/13993003.congress-2019.PA2829 (DOI)000507372403325 ()
Conference
European-Respiratory-Society (ERS) International Congress, Madrid, SPAIN, SEP 28-OCT 02, 2019.
Available from: 2020-03-17 Created: 2020-03-17 Last updated: 2020-03-17Bibliographically approved
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