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Pachchigar, S., Hannl, T. K. & Öhman, M. (2024). Ash Formation during Combustion of Rice Husks in Entrained Flow Conversion Conditions. Energy & Fuels
Open this publication in new window or tab >>Ash Formation during Combustion of Rice Husks in Entrained Flow Conversion Conditions
2024 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029Article in journal (Refereed) Epub ahead of print
Abstract [en]

This study investigates the detailed ash transformation process during the combustion of rice husks in entrained flow conditions. The experiments were conducted in a lab-scale drop tube furnace at 1200 and 1450 °C in pyrolysis/devolatilization (using N2) and combustion (using air) conditions. The detailed ash transformation process during the different fuel conversion stages in combustion (i.e., devolatilization and char combustion) was investigated by comparing the results obtained in the pyrolysis/devolatilization experiments with the combustion experiments. The resulting residual chars, ashes, and particulate matter (PM) were collected and characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM–EDS), X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES), ion chromatography (IC), and CHN analyses. Furthermore, the obtained results were interpreted via thermodynamic equilibrium calculations (TECs). For all investigated conditions, Si, Ca, and Mg were retained entirely in the coarse ash and char fractions (>1 μm). Meanwhile, K and P were found in coarse ash/char fractions and fine particulate fractions (<1 μm). A moderate, at 1200 °C, to high share, at 1450 °C, of the detected K and P was found in the fine particle fractions after combustion. The majority (>95%) of the detected S and Cl were volatilized during the experiments. The study showed an accumulation of minor ash-forming elements (i.e., K, Ca, Mg, P) on the inner part of rice husk chars, initiating melt formation during the char combustion stage. The identified melt at 1200 °C after combustion was rich in Si with minor amounts of K, Ca, Mg, and P. The share of molten ashes was increased at 1450 °C compared to that at 1200 °C. Overall, the results presented in this work reveal detailed insights into the ash transformation processes taking place in different parts of the fuel during the combustion of rice husks in entrained flow conditions.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2024
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-102986 (URN)10.1021/acs.energyfuels.4c01413 (DOI)
Funder
Swedish Energy Agency, 46443-2
Note

Full text: CC BY License;

This article has previously appeared as a manuscript in a thesis.

Available from: 2023-11-24 Created: 2023-11-24 Last updated: 2024-07-08
Hannl, T. K., Skoglund, N., Priščák, J., Öhman, M. & Kuba, M. (2024). Bubbling fluidized bed co-combustion and co-gasification of sewage sludge with agricultural residues with a focus on the fate of phosphorus. Fuel, 357(part B), Article ID 129822.
Open this publication in new window or tab >>Bubbling fluidized bed co-combustion and co-gasification of sewage sludge with agricultural residues with a focus on the fate of phosphorus
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2024 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 357, no part B, article id 129822Article in journal (Refereed) Published
Abstract [en]

In this work, the fate of the ash-forming elements during bubbling fluidized bed combustion and gasification of P-rich sewage sludge (SS) and mixtures with either Si-K-rich wheat straw (WS) or K-Ca-rich sunflower husks (SH) were investigated. The focus of the study was assessing the feasibility of using fuel blends in fluidized bed systems and potential P recovery from the resulting ashes. The used fuels were pure SS and mixtures including 90 wt.% WS (WSS) and 85 wt.% SH (SHS). The analyzed operating conditions were combustion (930–960 °C, λ: 1.2–1.5) and gasification (780–810 °C, λ: 0.4–0.7) in a 5 kW bench-scale reactor. Residual ash and char fractions were collected from different parts of the 5 kW bubbling fluidized bed (bed, cyclone, filter) and analyzed by CHN, SEM/EDS, XRD, and ICP-AES.

The conversion of the fuel mixtures achieved a steady state under the used process conditions except for the combustion of WSS, which led to the formation of large bed agglomerates with the bed material. The morphology of ash samples after combustion showed that SS fuel pellets mostly maintained their integrity during the experiment. In contrast, the ash and char particles from fuel mixtures were fragmented, and larger quantities were found in the cyclone, the filter, or on interior reactor surfaces. The fate of P was dominated by crystalline Ca-dominated whitlockites in all ash fractions, partially including K for the fuel mixtures SHS and WSS. 76–81 % of ingoing P was found in the bed residue after combustion and gasification of the SS-fuel. After conversion of the fuel mixtures SHS and WSS, the share was lower at 22–48 %, with larger shares of P in the entrained fractions (25–34 %). The quantity of identified crystalline compounds was lower after gasification than combustion, likely due to the limited interaction of ash-forming elements in the residual CHN matrix. Altogether, the results show that fuel mixtures of sewage sludge with agricultural residues could expand the fuel feedstock and enable P recovery. This may be used in the fuel and process design of upscaled fluidized bed processes or systems employing both combustion and gasification.

Place, publisher, year, edition, pages
Elsevier, 2024
Keywords
Combustion, Gasification, Biosolids, Nutrient recovery, Phosphate, Ash
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-95773 (URN)10.1016/j.fuel.2023.129822 (DOI)001105944200001 ()2-s2.0-85171736501 (Scopus ID)
Funder
Swedish Research Council Formas, dnr. 2018-00194
Note

Validerad;2023;Nivå 2;2023-10-10 (joosat);

CC BY 4.0 License

This article has previously appeared as a manuscript in a thesis.

Available from: 2023-03-02 Created: 2023-03-02 Last updated: 2024-03-07Bibliographically approved
Strandberg, A., Thyrel, M., Falk, J., Öhman, M. & Skoglund, N. (2024). Morphology and phosphate distribution in bottom ash particles from fixed-bed co-combustion of sewage sludge and two agricultural residues. Waste Management, 177, 56-65
Open this publication in new window or tab >>Morphology and phosphate distribution in bottom ash particles from fixed-bed co-combustion of sewage sludge and two agricultural residues
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2024 (English)In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 177, p. 56-65Article in journal (Refereed) Published
Abstract [en]

The purpose of this study was to provide detailed knowledge of the morphological properties of ash particles, including the volumetric fractions and 3D distributions of phosphates that lay within them. The ash particles came from digested sewage sludge co-combusted with K- and Si-rich wheat straw or K-rich sunflower husks. X-ray micro-tomography were combined with elemental composition and crystalline phase information to analyse the ash particles in 3D.

Analyses of differences in the X-ray attenuation enabled calculation of 3D phosphate distributions that showed high heterogeneity in the slag particles. This is underscored by a distinct absence of phosphates in iron-rich and silicon-rich parts. The slag from silicate-based wheat straw mixtures had lower average attenuation than that from sunflower husks mixtures, which contained more calcium. Calculated shares of phosphates between 7 and 17 vol% were obtained, where the highest value for a single assigned phosphate was observed in hard slag from wheat straw with 10 % sewage sludge. The porosity was notably higher for particles from pure wheat straw combustion (62 vol%), compared to the other samples (15–35 vol%). A high open pore volume fraction (60–97 vol%) indicates that a large part of the pores can be accessed by the surroundings. For all samples, more than 60 % of the discrete (closed) pores had an equivalent diameter < 30 μm, while the largest volume fraction consisted of pores with an equivalent diameter > 75 μm. Slag from sunflower husk mixtures had larger pore volumes and a greater relative number of discrete pores >75 µm compared to wheat straw mixtures.

Place, publisher, year, edition, pages
Elsevier Ltd, 2024
National Category
Other Environmental Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-104318 (URN)10.1016/j.wasman.2024.01.040 (DOI)38290348 (PubMedID)2-s2.0-85184148796 (Scopus ID)
Funder
Swedish Research Council, 2017-05331Bio4EnergySwedish Research Council Formas, 2018-00194, 2017-01613
Note

Validerad;2024;Nivå 2;2024-02-20 (joosat);

Funder: Carl-Fredrik von Horns fond and Stiftelsen för markvård till minne av Sanders Alburg, through the Royal Swedish Academy of Agriculture and Forestry (Grant No. GFS2018-0099)

Full text license: CC BY

Available from: 2024-02-20 Created: 2024-02-20 Last updated: 2024-02-20Bibliographically approved
Valizadeh, A., Faust, R., Skoglund, N., Forsberg, F., Öhman, M. & Knutsson, P. (2024). Role of Particle Geometry on the Structural Integrity of Sand and Rock Ilmenite Used as Oxygen Carrier in Combustion of Woody Biomass. Energy & Fuels, 38(11), 10114-10129
Open this publication in new window or tab >>Role of Particle Geometry on the Structural Integrity of Sand and Rock Ilmenite Used as Oxygen Carrier in Combustion of Woody Biomass
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2024 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 38, no 11, p. 10114-10129Article in journal (Refereed) Published
Abstract [en]

The role of particle geometry in the structural integrity of sand and rock ilmenite bed particles was studied under prolonged exposure to oxygen carrier-aided combustion (OCAC) conditions in a 12 MWth circulating fluidized bed (CFB) boiler. Woody biomass was used as fuel. Bed particles were collected at different stages of the exposure. Fresh bed particles were used as reference samples. All the materials were examined by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray microtomography (XMT). The obtained results showed that over time, sphericity diminishes in sand ilmenite, whereas the sphericity of rock ilmenite particles remains unchanged. For both bed types, it was noticed that cracks are mainly connected to the concave areas on the bed particle surface. It was also observed that in sand ilmenite, the bed particle layer predominantly forms on convex areas, resulting in nonuniform distribution, whereas in rock ilmenite, with infrequent convex and concave features, the layer is thicker and exhibits a more uniform distribution. Consequently, the bed particle layer in rock ilmenite plays a higher protection against the outward migration of iron. This, coupled with a lower frequency of concave areas, contributes to a reduced average volume fraction of porous regions and cracks, which makes rock ilmenite structurally more resistant to breakage than sand ilmenite. Notably, the difference in the structural integrity of the two bed types becomes even more pronounced with longer exposure times.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2024
National Category
Energy Engineering
Research subject
Energy Engineering; Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-105155 (URN)10.1021/acs.energyfuels.4c00658 (DOI)001225282000001 ()2-s2.0-85192850521 (Scopus ID)
Funder
Swedish Energy Agency, P46533-1Swedish Research Council, 2023-03500
Note

Validerad;2024;Nivå 2;2024-06-28 (hanlid);

Full text license: CC BY;

This article has previously appeared as a manuscript in a thesis.

Available from: 2024-04-19 Created: 2024-04-19 Last updated: 2024-06-28Bibliographically approved
Valizadeh, A., Skoglund, N., Forsberg, F., Lycksam, H. & Öhman, M. (2024). Role of surface morphology in bed particle layer formation on quartz bed particles in fluidized bed combustion of woody biomass. Fuel, 357(part A), Article ID 129702.
Open this publication in new window or tab >>Role of surface morphology in bed particle layer formation on quartz bed particles in fluidized bed combustion of woody biomass
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2024 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 357, no part A, article id 129702Article in journal (Refereed) Published
Abstract [en]

The influence of quartz bed particle surface morphology on the bed particle layer and crack layer formation process in fluidized bed combustion of woody biomass was investigated in this work. Bed material samples were collected at different sampling times from the startup with a fresh bed in industrial scale bubbling fluidized bed (BFB) and circulating fluidized bed (CFB) boilers, both utilizing woody biomass. X-ray microtomography (XMT) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) were employed to characterize bed particle layers and crack layers in the samples. Results showed that there is a noticeable difference between the bed layer characteristics over the so-called “concave” and “convex”-shaped morphologies on the bed particle surface with respect to layer formation. The concave areas are mainly covered with a thin inner layer, whilst the convex display a comparably thick inner layer and an outer layer. In addition, 3D images of the particles revealed that the crack layers mainly originate from concave areas where the particle is less protected by an outer bed particle layer in conjunction with cracks in the inner layer.

Place, publisher, year, edition, pages
Elsevier Ltd, 2024
Keywords
Bed material, Industrial-scale, Time-resolved, X-ray tomography
National Category
Energy Engineering
Research subject
Energy Engineering; Experimental Mechanics; Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-101365 (URN)10.1016/j.fuel.2023.129702 (DOI)001070700200001 ()2-s2.0-85170026881 (Scopus ID)
Funder
Swedish Energy Agency, no. 46533-1
Note

Validerad;2023;Nivå 2;2023-09-18 (joosat);

CC BY 4.0 License;

For correction, see: Valizadeh A., Skoglund N., Forsberg F., Lycksam H., Öhman M., (2024). Corrigendum to “Role of surface morphology in bed particle layer formation on quartz bed particles in fluidized bed combustion of woody biomass” [Fuel 357(Part A) (2024) 129702]. Fuel. 364 131320. doi https://doi.org/10.1016/j.fuel.2024.131320

Available from: 2023-09-18 Created: 2023-09-18 Last updated: 2024-04-19Bibliographically approved
Wetterlund, E., Andreas, L., Bagheri, M., Bauer, T., Falk, J., Hannl, T. K., . . . Öhman, M. (2024). Smart Waste Treatment in the Circular Economy. Luleå: Luleå University of Technology
Open this publication in new window or tab >>Smart Waste Treatment in the Circular Economy
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2024 (English)Report (Other (popular science, discussion, etc.))
Abstract [en]

This project has targeted utilisation of infrastructure for organic waste treatment in Sweden, in particular sewage sludge, to achieve increased production of high-value materials and energy carriers, reduced use of primary resources, and improved economic performance. We have investigated the sewage sludge management system as a socio-technical system facing a change, with integral connections to the energy and waste systems.

In conclusion, there is no silver bullet for the future of sewage sludge management. Indeed, it would have to be a full clip of silver bullets, as we found that a mishmash of different barriers –technical, economic, legal, and related to public perception – creates uncertainty that hinders progress regarding both sustainable long-term strategies and technological advancement. The Swedish sewage sludge management is largely fragmented, highlighting the need to shift directionto a more holistic approach. This can help actors address common issues rather than focussing solely on activity-specific problems. Introducing new legislation could be a key step, as the current specific legislation on sewage sludge has a seemingly insignificant role for today’s sludge management, compared to other legislation and the voluntary certification.

We have formulated six overall research highlights, to outline both published results and meta-conclusions based on combined insights. Each highlight is described separately in this report.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2024. p. 27
National Category
Environmental Management
Research subject
Energy Engineering; Waste Science and Technology; Law; Economics
Identifiers
urn:nbn:se:ltu:diva-105334 (URN)978-91-8048-447-3 (ISBN)
Projects
SMart Avfallsbehandling i Cirkulär eKonomi (SMACK) (Smart waste treatment in the circular economy)
Funder
Swedish Research Council Formas, 2018-00194
Available from: 2024-05-03 Created: 2024-05-03 Last updated: 2024-05-03Bibliographically approved
Valizadeh, A., Skoglund, N., Forsberg, F., Lycksam, H. & Öhman, M. (2023). A comparative study in 3D of bed particle layer characteristics in quartz and K-feldspar from fluidized bed combustion of woody biomass using X-ray microtomography. Paper presented at 28th International Conference on the Impact of Fuel Quality on Power Production and the Environment, Åre, Sweden, September 19-23, 2022. Fuel, 342, Article ID 127707.
Open this publication in new window or tab >>A comparative study in 3D of bed particle layer characteristics in quartz and K-feldspar from fluidized bed combustion of woody biomass using X-ray microtomography
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2023 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 342, article id 127707Article in journal (Refereed) Published
Abstract [en]

Bed particle layer and crack layer characteristics at different ages were studied for quartz and K-feldspar bed particles from a 30 MWth bubbling fluidized bed and a 90 MWth circulating fluidized bed, both using woody biomass as fuel. X-ray microtomography (XMT) was utilized to determine the bed particle layer distribution on the bed particles' surface. For each bed particle type, the average bed particle layer thickness as well as average volume fractions of the bed particle layer and crack layers to the entire bed particle volume were determined at three different bed particle ages by utilizing XMT analysis. Comparison of the two different bed particle types showed that K-feldspar retains a thinner bed particle layer in both conversion processes compared to quartz. Crack layers were observed extensively in quartz bed particles to the extent of 19.3 vol% and 32.1 vol% after 13 days in the BFB and the CFB, respectively, which could cause deposition of the bed particle fragments. On the contrary, K-feldspar has almost no tendency toward forming crack layers.

Place, publisher, year, edition, pages
Elsevier Ltd, 2023
Keywords
Bed particle layer formation, Combustion, Fluidized bed, Woody biomass, X-ray microtomography
National Category
Energy Engineering
Research subject
Energy Engineering; Experimental Mechanics; Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-95819 (URN)10.1016/j.fuel.2023.127707 (DOI)000946690800001 ()2-s2.0-85148664496 (Scopus ID)
Conference
28th International Conference on the Impact of Fuel Quality on Power Production and the Environment, Åre, Sweden, September 19-23, 2022
Funder
Swedish Energy Agency, 46533-1
Note

Godkänd;2023;Nivå 0;2023-03-08 (joosat);Konferensartikel i tidskrift

Part of special issue: 28th International Conference on the Impact of Fuel Quality on Power Production and the Environment, Edited by Flemming J. Frandsen, Stanley Harding, Terry Wall, Markus Broström, Maria Zevenhoven

Licens fulltext: CC BY License

Available from: 2023-03-08 Created: 2023-03-08 Last updated: 2024-04-19Bibliographically approved
Falk, J., Hannl, T. K., Öhman, M., Hedayati, A. & Skoglund, N. (2023). Ash Transformation during Fixed-Bed Co-combustion of Sewage Sludge and Agricultural Residues with a Focus on Phosphorus. ACS Omega, 8(14), 13162-13176
Open this publication in new window or tab >>Ash Transformation during Fixed-Bed Co-combustion of Sewage Sludge and Agricultural Residues with a Focus on Phosphorus
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2023 (English)In: ACS Omega, E-ISSN 2470-1343, Vol. 8, no 14, p. 13162-13176Article in journal (Refereed) Published
Abstract [en]

This work investigates the ash transformation during fixed-bed co-combustion of sewage sludge mixtures with the agricultural residues wheat straw and sunflower husks, focusing on the fate of phosphorus (P) in the resulting ash fractions. The study aims to determine suitable process parameters for fixed-bed combustion of fuels previously investigated in single-pellet experiments. The pure fuels and fuel mixtures were combusted in a 20 kWth residential pellet burner while monitoring the flue gas composition, temperature, and particulate matter formation. Subsequently, the different ash fractions were collected and characterized by CHN, SEM/EDS, and XRD analysis. The results showed that co-combustion of sewage sludge and agricultural residues reduced the formation of particulate matter as well as the formation of slag. Co-combustion of sewage sludge with either agricultural residue resulted in a change in phosphate speciation, displaying higher shares of Ca and lower shares of Fe and Al in the formed orthophosphates as well as amorphous phases containing higher shares of K. The formation of K-bearing phosphates was hindered by the spatial association of P with Ca and Fe in the sewage sludge, the incorporation of available K in K-Al silicates, and the depletion of K in the P-rich melt phase. Compared to mono-combustion, co-combustion experiments showed the potential for improving the combustion performance and reducing the risk of slag formation. The outcome suggests that co-combustion is a feasible path to integrate waste streams in fixed-bed energy conversion with simultaneous formation of phosphates enabling P recovery.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2023
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-93429 (URN)10.1021/acsomega.3c00415 (DOI)000966980600001 ()2-s2.0-85151894910 (Scopus ID)
Funder
Swedish Research Council Formas, 2018-00194, 2017-01613Bio4EnergySwedish Research Council, 2017-05331
Note

Validerad;2023;Nivå 2;2023-04-19 (hanlid);

This article has previously appeared as a manuscript in a thesis.

Available from: 2022-10-04 Created: 2022-10-04 Last updated: 2024-03-07Bibliographically approved
Böhlenius, H., Öhman, M., Granberg, F. & Persson, P.-O. (2023). Biomass production and fuel characteristics from long rotation poplar plantations. Biomass and Bioenergy, 178, Article ID 106940.
Open this publication in new window or tab >>Biomass production and fuel characteristics from long rotation poplar plantations
2023 (English)In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 178, article id 106940Article in journal (Refereed) Published
Abstract [en]

One of the key elements in this transition is the securing of a large supply of sustainable biomass. In this study, the feedstock potential of long rotation poplar plantations (12–30 years with diameter of 15 of 30 cm) was determined and the properties of poplar biomass fuel were analyzed with the aim of using thermochemical conversion methods to produce biofuel. Our results demonstrate that Sweden has great potential for producing biofuels from long rotation poplar plantations, with a total of 1.8 million hectares (ha) consisting of arable (0.5 million ha) and forested arable land (1.3 million ha). Based on available land and biomass production potential, our results indicate that 10 million Mg DW could be produced annually. Regions in mid/southern Sweden have the largest potential (larger areas and higher biomass production. Our results further suggest that poplar biomass from these plantations has fuel characteristics similar to forest fuels from other conifer tree species, making the biomass suitable as feedstock for biofuel production based on thermochemical conversion methods. If 25% of the available land were used, 7.6 TWh methanol biofuels could be produced annually from 16 biofuel plants, using 160,000 Mg DW yr−1, primarily located in the southern part of Sweden. Two counties (Skåne and Västra Götaland) would be able to support their biofuel plants using poplar plantations as feedstock. Stable biofuel production in the other counties would depend on collaborating with neighboring counties.

Place, publisher, year, edition, pages
Elsevier Ltd, 2023
National Category
Renewable Bioenergy Research Bioenergy
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-101975 (URN)10.1016/j.biombioe.2023.106940 (DOI)001088455700001 ()2-s2.0-85173605025 (Scopus ID)
Funder
Swedish Energy Agency
Note

Validerad;2023;Nivå 2;2023-11-08 (marisr);

License full text: CC BY

Available from: 2023-10-31 Created: 2023-10-31 Last updated: 2023-11-08Bibliographically approved
Priščák, J., Valizadeh, A., Öhman, M., Hofbauer, H. & Kuba, M. (2023). Effect of time-dependent layer formation on the oxygen transport capacity of ilmenite during combustion of ash-rich woody biomass. Fuel, 353, Article ID 129068.
Open this publication in new window or tab >>Effect of time-dependent layer formation on the oxygen transport capacity of ilmenite during combustion of ash-rich woody biomass
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2023 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 353, article id 129068Article in journal (Refereed) Published
Abstract [en]

Oxygen carrier aided combustion (OCAC) is a novel technology that aims to enhance combustion of heterogenous fuels by replacing the inert bed material with an active oxygen carrier. One of the promising oxygen carriers is natural ilmenite which shows decent oxygen transport capacity and mechanical stability under OCAC operating conditions. However, interactions between ilmenite and woody biomass ash lead to the formation of a calcium-rich ash layer, which affects the ability of the oxygen carrier (OC) to transfer oxygen throughout the boiler and subsequently decreases the combustion efficiency. This paper focuses on the time-dependent morphological and compositional changes in ilmenite bed particles and the consequence effects on the oxygen transport capacity and reactivity of ilmenite. Ilmenite utilized in this study was investigated in a 5 kW bubbling fluidized bed combustion unit, utilizing ash-rich bark pellets as fuel. A negative effect of iron migration on the oxygen transport capacity was observed in ilmenite bed particles after 6 h of operation in the bubbling fluidized bed reactor. The decrease in the oxygen transport capacity of ilmenite was found to correlate with the increased exposure time in the fluidized bed reactor and was caused by the migration and subsequent erosion of Fe from the ilmenite particles. On the other hand, the older bed particles show an increase in reaction rate, presumably due to the catalytic activity of the calcium-enriched outer layer on the bed particle surface.

Place, publisher, year, edition, pages
Elsevier Ltd, 2023
Keywords
Ash layer, Ilmenite, OCAC, Oxygen transport
National Category
Energy Engineering Other Chemical Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-99289 (URN)10.1016/j.fuel.2023.129068 (DOI)001047077300001 ()2-s2.0-85164690459 (Scopus ID)
Funder
Swedish Energy Agency, P46533-1
Note

Validerad;2023;Nivå 2;2023-08-08 (joosat);

Available from: 2023-08-08 Created: 2023-08-08 Last updated: 2024-04-19Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-2319-0906

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