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Boman, Christoffer
Publications (10 of 77) Show all publications
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
Sandström, K., Boman, C., Weidemann, E. & Broström, M. (2019). Fluorine reactions in MSW combustion. In: EUBCE 2019: . Paper presented at EUBCE 2019, 27th European Biomass Conference & Exhibition, 27-30 May, Lisbon, Portugal.
Open this publication in new window or tab >>Fluorine reactions in MSW combustion
2019 (English)In: EUBCE 2019, 2019Conference paper, Poster (with or without abstract) (Other academic)
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-162798 (URN)
Conference
EUBCE 2019, 27th European Biomass Conference & Exhibition, 27-30 May, Lisbon, Portugal
Available from: 2019-08-28 Created: 2019-08-28 Last updated: 2019-09-06Bibliographically 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
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
Zhu, Y., van Eyk, P. J., Boman, C., Broström, M., Kirtania, K., Piotrowska, P., . . . Ashman, P. J. (2018). Preliminary understanding on the ash behavior of algae during co-gasification in an entrained flow reactor. Fuel processing technology, 175, 26-34
Open this publication in new window or tab >>Preliminary understanding on the ash behavior of algae during co-gasification in an entrained flow reactor
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2018 (English)In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 175, p. 26-34Article in journal (Refereed) Published
Abstract [en]

Algae are considered as a promising alternative fuel to produce energy due to its advantages such as high production yield, short growth cycle and flexible growing environment. Unfortunately, ash-related issues restrict its thermochemical utilization due to the high ash content and especially the high alkali metal concentration. In this paper, the gasification performance and ash behavior were experimentally analysed for three macro- and micro-algal species. Clear differences in the proximate and ultimate compositions were found between the cultivated algae used in this study and macroalgae (seaweed) harvested from the marine environments. Algal biomass generally contained higher Na and P contents than lignocellulosic biomass. Microalgae also had a relatively high mineral content due to the impurities in the harvesting process which included centrifugal pumping followed by sedimentation. Co-gasification of 20 wt% algae with softwood was investigated using an entrained flow reactor. The addition of both macroalgal species Derbersia tenuissima and Oedogonium to softwood had a limited influence on the gas yields and carbon conversion. On the other hand, the addition of the microalgal species Scenedesmus significantly decreased the main gas yields and carbon conversion. Moreover, the addition of algae clearly changed the residual ash composition of the base fuel. Finally, a preliminary understanding of the ash behavior of the tested algae blends was obtained through the analysis of the fuel ashes and the collected residual ashes. Fouling and corrosion were presumably occurred during the co-gasification of wood/macroalgae blends in view of the high alkali metal content. Microalga Scenedesmus had a high mineral content which could potentially capture the alkali metal in the ash and mitigate fouling when gasified with softwood. The growing environment and harvesting method were found to be significantly affecting the ash behavior implying the need for careful consideration regarding co-gasification process.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
algae, ash behavior, co-gasification, fouling, ash transformation
National Category
Energy Engineering Bioenergy
Identifiers
urn:nbn:se:umu:diva-147730 (URN)10.1016/j.fuproc.2018.02.028 (DOI)000432100300004 ()2-s2.0-85042857511 (Scopus ID)
Projects
Bio4Energy
Available from: 2018-05-16 Created: 2018-05-16 Last updated: 2019-09-02Bibliographically approved
Boström, D., Skoglund, N., Boman, C., Öhman, M., Broström, M. & Backman, R. (2017). Ash transformation chemistry during combustion of biomass, theory and technical applications. Paper presented at 254th National Meeting and Exposition of the American-Chemical-Society (ACS) on Chemistry's Impact on the Global Economy, AUG 20-24, 2017, Washington, DC. Abstract of Papers of the American Chemical Society, 254
Open this publication in new window or tab >>Ash transformation chemistry during combustion of biomass, theory and technical applications
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2017 (English)In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 254Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
American Chemical Society (ACS), 2017
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-147225 (URN)000429525604122 ()
Conference
254th National Meeting and Exposition of the American-Chemical-Society (ACS) on Chemistry's Impact on the Global Economy, AUG 20-24, 2017, Washington, DC
Note

Meeting Abstract: 23

Available from: 2018-05-02 Created: 2018-05-02 Last updated: 2018-06-09Bibliographically approved
Boman, C., Öhman, M., Broström, M., Skoglund, N., Schmidt, F. M., Backman, R. & Boström, D. (2017). Ash transformation chemistry in biomass fixed beds with focus on slagging and aerosols: 20 years of research and new developments. Paper presented at 254th National Meeting and Exposition of the American-Chemical-Society (ACS) on Chemistry's Impact on the Global Economy, AUG 20-24, 2017, Washington, DC. Abstract of Papers of the American Chemical Society, 254
Open this publication in new window or tab >>Ash transformation chemistry in biomass fixed beds with focus on slagging and aerosols: 20 years of research and new developments
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2017 (English)In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 254Article in journal, Meeting abstract (Other academic) Published
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-148191 (URN)
Conference
254th National Meeting and Exposition of the American-Chemical-Society (ACS) on Chemistry's Impact on the Global Economy, AUG 20-24, 2017, Washington, DC
Note

Meeting Abstract: 24

Available from: 2018-05-30 Created: 2018-05-30 Last updated: 2018-06-09
Sundberg, P., Fagerström, J., Rebbling, A., Skoglund, N., Hermansson, S., Tullin, C., . . . Boman, C. (2017). Biomass and peat co-combustion in full scale grate boilers - a primary measure for reduction of fine particle emissions. In: : . Paper presented at 5th Central European Biomass Conference, Graz, Austria, January 18-20, 2017.
Open this publication in new window or tab >>Biomass and peat co-combustion in full scale grate boilers - a primary measure for reduction of fine particle emissions
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2017 (English)Conference paper, Poster (with or without abstract) (Refereed)
National Category
Energy Engineering Other Chemistry Topics
Identifiers
urn:nbn:se:umu:diva-130611 (URN)
Conference
5th Central European Biomass Conference, Graz, Austria, January 18-20, 2017
Available from: 2017-01-26 Created: 2017-01-26 Last updated: 2018-06-09
Nazelius, I.-L., Boström, D., Rebbling, A., Boman, C. & Öhman, M. (2017). Fuel indices for estimation of slagging of phosphorus-poor biomass in fixed bed combustion. Energy & Fuels, 31(1), 904-915
Open this publication in new window or tab >>Fuel indices for estimation of slagging of phosphorus-poor biomass in fixed bed combustion
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2017 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 31, no 1, p. 904-915Article in journal (Refereed) Published
Abstract [en]

The market for solid biofuels will grow rapidly during the coming years, and there will be a great demand for raw materials. This will force the existing fuel base to also cover wooden materials of lower qualities as well as agricultural raw materials and residues, which often show unfavorable ash-melting temperatures. This may lead to combustion-related problems. Thus, for the utilization of lower quality fuels, it is important to be able to predict potential fuel ash-related problems such as slagging. In light of this, the first objective of the present paper was to evaluate the applicability of previously defined indices for slagging of biomass fuels (phosphorus-poor) in fixed bed combustion. The evaluation showed that none of the previously suggested indices in the literature are suitable for qualitative (nor quantitative) prediction of slagging during fixed bed combustion of P-poor biomass fuels. Hence, a second objective was to develop improved novel fuel indices that can be applied to estimate the slagging of phosphorus-poor biomass in fixed bed combustion. The novel fuel indices give a qualitative prediction of the slagging tendency in biomass fixed bed combustion but still needs additional work to further extend the compositional range as well as to fine tune the indices' boundaries.

National Category
Energy Engineering Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-131876 (URN)10.1021/acs.energyfuels.6b02563 (DOI)000392553800094 ()
Projects
Bio4Energy
Available from: 2017-02-24 Created: 2017-02-24 Last updated: 2019-09-02Bibliographically approved
Nyström, R., Lindgren, R., Avagyan, R., Westerholm, R., Lundstedt, S. & Boman, C. (2017). Influence of Wood Species and Burning Conditions on Particle Emission Characteristics in a Residential Wood Stove. Energy & Fuels, 31(5), 5514-5524
Open this publication in new window or tab >>Influence of Wood Species and Burning Conditions on Particle Emission Characteristics in a Residential Wood Stove
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2017 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 31, no 5, p. 5514-5524Article in journal (Refereed) Published
Abstract [en]

Emissions from small-scale residential biomass combustion are a major source of indoor and outdoor particulate matter (PM) air pollution, and the performance of stoves, boilers, and fireplaces have been shown to be influenced both by fuel properties, technology, and user behavior (firing procedures). Still, rather scarce information is available regarding the relative importance of these variables for the particle characteristics and emissions of different particulate components, e.g., soot, polycyclic aromatic hydrocarbons (PAHs), oxy-PAH, and metals. In particular, the behavior of different wood fuels under varying firing procedures and combustion conditions has not been studied thoroughly. Therefore, the objective of this work was to elucidate the influence of wood species and combustion conditions on particle emission characteristics in a typical Nordic residential wood stove. The emissions from four different wood species were investigated at two controlled combustion conditions, including nominal and high burn rates, with a focus on physical and chemical properties of the fine particulate matter. Considerably elevated carbonaceous particle emissions (soot and organics) were found during high burn rate conditions, which were associated with a shift in particle number size distribution toward a higher fraction of larger particles. In some cases, as here seen for pine, the specific fuel properties can affect the combustion performance and thereby also influence particle and PAH emissions. For the inorganic ash particles, the content in the fuel, and not burning conditions, was found to be the main determining factor, as seen by the increased emissions of alkali salts for aspen. Wood stove emission data on 11 specific oxy-PAHs, together with 45 PAHs, were combined with controlled variations of burning conditions and fuels. The oxy-PAH/PAH ratio during a high burn rate was observed to increase, suggesting an enrichment of particulate oxy-PAH. Accordingly, the main influence on emission performance and particle characteristics was seen between different burn rates, and this study clearly illustrates the major importance of proper operation to avoid unfavorable burning condition, regardless of the wood species used.

National Category
Bioenergy
Identifiers
urn:nbn:se:umu:diva-136337 (URN)10.1021/acs.energyfuels.6b02751 (DOI)000402023600098 ()
Projects
Bio4Energy
Funder
Swedish Research Council, 621-2012-3802
Available from: 2017-06-19 Created: 2017-06-19 Last updated: 2019-09-02Bibliographically approved
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