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Kuba, Matthias
Publications (7 of 7) Show all publications
Kuba, M., Fürsatz, K., Janisch, D., Aziaba, K., Chlebda, D., Łojewska, J., . . . Hofbauer, H. (2021). Surface characterization of ash-layered olivine from fluidized bed biomass gasification. Biomass Conversion and Biorefinery, 11(1), 29-38
Open this publication in new window or tab >>Surface characterization of ash-layered olivine from fluidized bed biomass gasification
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2021 (English)In: Biomass Conversion and Biorefinery, ISSN 2190-6815, E-ISSN 2190-6823, Vol. 11, no 1, p. 29-38Article in journal (Refereed) Published
Abstract [en]

The present study aims to present a comprehensive characterization of the surface of ash-layered olivine bed particles from dual fluidized bed gasification. It is well known from operation experience at industrial gasification plants that the bed material is activated during operation concerning its positive influence on gasification reactions. This is due to the built up of ash layers on the bed material particles; however, the chemical mechanisms are not well understood yet. Olivine samples from long-term operation in an industrial-scale gasification plant were investigated in comparison to fresh unused olivine. Changes of the surface morphology due to Ca-enrichment showed a significant increase of their surface area. Furthermore, the Ca-enrichment on the ash layer surface was distinctively associated to CaO being present. The presence of CaO on the surface was proven by adsorption tests of carbon monoxide as model compound. The detailed characterization contributes to a deeper understanding of the surface properties of ash layers and forms the basis for further investigations into their influence on gasification reactions.

Place, publisher, year, edition, pages
Springer, 2021
Keywords
Biomass, Gasification, Ash layer formation, Surface characterization
National Category
Energy Engineering Applied Mechanics
Research subject
Experimental Mechanics; Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-80467 (URN)10.1007/s13399-020-00863-2 (DOI)000546925500001 ()2-s2.0-85087696849 (Scopus ID)
Note

Validerad;2021;Nivå 2;2021-02-18 (alebob);

Finansiär: Austrian Research Promotion Agency (FFG)

Available from: 2020-08-19 Created: 2020-08-19 Last updated: 2023-09-05Bibliographically approved
Hannl, T. K., Sefidari, H., Kuba, M., Skoglund, N. & Öhman, M. (2021). Thermochemical equilibrium study of ash transformation during combustion and gasification of sewage sludge mixtures with agricultural residues with focus on the phosphorus speciation. Biomass Conversion and Biorefinery, 11(1), 57-68
Open this publication in new window or tab >>Thermochemical equilibrium study of ash transformation during combustion and gasification of sewage sludge mixtures with agricultural residues with focus on the phosphorus speciation
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2021 (English)In: Biomass Conversion and Biorefinery, ISSN 2190-6815, E-ISSN 2190-6823, Vol. 11, no 1, p. 57-68Article in journal (Refereed) Published
Abstract [en]

The necessity of recycling anthropogenically used phosphorus to prevent aquatic eutrophication and decrease the economic dependency on mined phosphate ores encouraged recent research to identify potential alternative resource pools. One of these resource pools is the ash derived from the thermochemical conversion of sewage sludge. This ash is rich in phosphorus, although most of it is chemically associated in a way where it is not plant available. The aim of this work was to identify the P recovery potential of ashes from sewage sludge co-conversion processes with two types of agricultural residues, namely wheat straw (rich in K and Si) and sunflower husks (rich in K), employing thermodynamic equilibrium calculations. The results indicate that both the melting behavior and the formation of plant available phosphates can be enhanced by using these fuel blends in comparison with pure sewage sludge. This enhanced bioavailability of phosphates was mostly due to the predicted formation of K-bearing phosphates in the mixtures instead of Ca/Fe/Al phosphates in the pure sewage sludge ash. According to the calculations, gasification conditions could increase the degree of slag formation and enhance the volatilization of K in comparison with combustion conditions. Furthermore, the possibility of precipitating phosphates from ash melts could be shown. It is emphasized that the results of this theoretical study represent an idealized system since in practice, non-equilibrium influences such as kinetic limitations and formation of amorphous structures may be significant. However, applicability of thermodynamic calculations in the prediction of molten and solid phases may still guide experimental research to investigate the actual phosphate formation in the future.

Place, publisher, year, edition, pages
Springer, 2021
Keywords
Sewage sludge, Wheat straw, Sunflower husks, Modeling, Phosphorus recovery
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-79370 (URN)10.1007/s13399-020-00772-4 (DOI)000537675600001 ()2-s2.0-85085986587 (Scopus ID)
Funder
Swedish Research Council Formas, 942-2015-619, 2017-01613Swedish Research Council, 2016-04380
Note

Validerad;2021;Nivå 2;2021-02-19 (alebob)

Available from: 2020-06-10 Created: 2020-06-10 Last updated: 2023-09-05Bibliographically approved
Häggström, G., Fürsatz, K., Kuba, M., Skoglund, N. & Öhman, M. (2020). Fate of Phosphorus in Fluidized Bed Cocombustion of Chicken Litter with Wheat Straw and Bark Residues. Energy & Fuels, 34(2), 1822-1829
Open this publication in new window or tab >>Fate of Phosphorus in Fluidized Bed Cocombustion of Chicken Litter with Wheat Straw and Bark Residues
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2020 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 34, no 2, p. 1822-1829Article in journal (Refereed) Published
Abstract [en]

This study aims to determine the fate of P during fluidized bed co-combustion of chicken litter (CL) with K-rich fuels [e.g., wheat straw (WS)] and Ca-rich fuels (bark). The effect of fuel blending on phosphate speciation in ash was investigated. This was performed by chemical characterization of ash fractions to determine which phosphate compounds had formed and identify plausible ash transformation reactions for P. The ash fractions were produced in combustion experiments using CL and fuel blends with 30% CL and WS or bark (B) at 790–810 °C in a 5 kW laboratory-scale bubbling fluidized bed. Potassium feldspar was used as the bed material. Bed ash particles, cyclone ash, and particulate matter (PM) were collected and subjected to chemical analysis with scanning electron microscopy–energy-dispersive X-ray spectrometry (SEM–EDS) and X-ray diffraction. P was detected in coarse ash fractions only, that is, bed ash, cyclone ash, and coarse PM fraction (>1 μm); no P could be detected in the fine PM fraction (<1 μm). SEM–EDS analysis showed that P was mainly present in K–Ca–P-rich areas for pure CL as well as in the ashes from the fuel blends of CL with WS or B. In the WS blend, P was found together with Si in these areas. The crystalline compound containing P was hydroxyapatite in all cases as well as whitlockite in the cases of pure CL and WS blend, of which the latter compound has been previously identified as a promising plant nutrient. The ash fractions from CL and bark blend only contained P in hydroxyapatite. Co-combustion of CL together with WS appears to be promising for P recovery, and ashes with this composition could be further studied in plant growth experiments.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2020
Keywords
Phosphates, Chemical reactions, Fuels, Reaction products, Materials
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-78115 (URN)10.1021/acs.energyfuels.9b03652 (DOI)000518215400072 ()2-s2.0-85080856092 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-03-20 (alebob)

Available from: 2020-03-20 Created: 2020-03-20 Last updated: 2023-09-05Bibliographically 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
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-73937 (URN)10.1016/j.apenergy.2019.04.112 (DOI)000469891900044 ()2-s2.0-85064643200 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-05-14 (johcin)

Available from: 2019-05-14 Created: 2019-05-14 Last updated: 2023-09-05Bibliographically approved
Faust, R., Hannl, T. K., Berdugo Vilches, T., Kuba, M., Öhman, M., Seemann, M. & Knutsson, P. (2019). Layer Formation on Feldspar Bed Particles during Indirect Gasification of Wood. 1. K-Feldspar. Energy & Fuels, 33(8), 7321-7332
Open this publication in new window or tab >>Layer Formation on Feldspar Bed Particles during Indirect Gasification of Wood. 1. K-Feldspar
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2019 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 33, no 8, p. 7321-7332Article in journal (Refereed) Published
Abstract [en]

The choice of bed material for biomass gasification plays a crucial role for the overall efficiency of the process. Olivine is the material conventionally used for biomass gasification due to the observed activity of olivine toward cracking of unwanted tars. Despite its catalytic activity, olivine contains high levels of chromium, which complicates the deposition of used bed material. Feldspar has shown the same activity as olivine when used as a bed material in biomass gasification. As opposed to olivine, feldspar does not contain environmentally hazardous compounds, which makes it a preferred alternative for further applications. The interaction of bed material and ash heavily influences the properties of the bed material. In the present study interactions between feldspar and main ash compounds of woody biomass in an indirect gasification system were investigated. Bed material samples were collected at different time intervals and analyzed with SEM-EDS and XRD. The obtained analysis results were then compared to thermodynamic models. The performed study was divided in two parts: in part 1 (the present paper), K-rich feldspar was investigated, whereas Na-rich feldspar is presented in part 2 of the study (DOI: 10.1021/acs.energyfuels.9b01291). From the material analysis performed, it can be seen that, as a result of the bed materials’ interactions with the formed ash compounds, the latter were first deposited on the surface of the K-feldspar particles and later resulted in the formation of Ca- and Mg-rich layers. The Ca enriched in the layers further reacted with the feldspar, which led to its diffusion into the particles and the formation of CaSiO3 and KAlSiO4. Contrary to Ca, Mg did not react with the feldspar and remained on the surface of the particles, where it was found as Mg- or Ca-Mg-silicates. As a result of the described interactions, layer separation was noted after 51 h with an outer Mg-rich layer and an inner Ca-rich layer. Due to the development of the Ca- and Mg-rich layers and the bed material–ash interactions, crack formation was observed on the particles’ surfaces.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
Keywords
Dual Fluidized Bed, Bed Material, Wood, Feldspar
National Category
Chemical Process Engineering Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-75491 (URN)10.1021/acs.energyfuels.9b01291 (DOI)000481569100046 ()2-s2.0-85070922502 (Scopus ID)
Funder
Swedish Energy Agency, P46533-1 and P42034-1
Note

Validerad;2019;Nivå 2;2019-09-09 (johcin)

Available from: 2019-08-13 Created: 2019-08-13 Last updated: 2023-09-05Bibliographically approved
Hannl, T. K., Faust, R., Kuba, M., Knutsson, P., Berdugo Vilches, T., Seemann, M. & Öhman, M. (2019). Layer Formation on Feldspar Bed Particles during Indirect Gasification of Wood. 2. Na-Feldspar. Energy & Fuels, 33(8), 7333-7346
Open this publication in new window or tab >>Layer Formation on Feldspar Bed Particles during Indirect Gasification of Wood. 2. Na-Feldspar
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2019 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 33, no 8, p. 7333-7346Article in journal (Refereed) Published
Abstract [en]

Selecting a suitable bed material for the thermochemical conversion of a specific feedstock in a fluidized bed system requires identification of the characteristics of potential bed materials. An essential part of these characteristics is the interaction of the bed material with feedstock ash in a fluidized bed, which leads to layer formation and morphology changes. For this purpose, the interaction of feldspar bed material with the main ash-forming elements in wood ash (Ca, K, Mg, Si) in an indirect gasification system was analyzed using SEM-EDS, XRD, and thermodynamic modeling. In part 1 of this work (DOI: 10.1021/acs.energyfuels.9b01291), the layer formation on K-feldspar dominated by Ca reaction and ash deposition was investigated. The aim of this second part of the work was to determine the time-dependent layer formation on Na-feldspar and compare the results with the findings for K-feldspar. Interaction of Na-feldspar with ash-derived elements resulted in different layers on Na-feldspar: K reaction layers, where K replaced Na and Si shares decreased; Ca reaction layers, where Ca enriched and reacted with the Na-feldspar; and ash deposition layers, where wood ash elements accumulated on the surface. Ca reaction layers were formed first and became continuous on the surface before K reaction layers and ash deposition layers were detected. Cracks and crack layer formation in the Na-feldspar particles were found after several days of operation. The layer compositions and growth rates indicate that the diffusion of Ca and K plays an essential role in the formation of Ca reaction and K reaction layers. The reaction with Ca and the crack formation coincide with the interaction previously found for quartz and K-feldspar. In contrast to K-feldspar, Na-feldspar showed high potential for reaction with K. The findings indicate that the reaction of Na-feldspar with ash-derived K makes Na-feldspar a less stable bed material than K-feldspar during the thermochemical conversion of K-rich feedstocks in a fluidized bed system.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
Keywords
Dual Fluidized Bed, Bed Material, Wood, Feldspar
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-75473 (URN)10.1021/acs.energyfuels.9b01292 (DOI)000481569100047 ()2-s2.0-85070917597 (Scopus ID)
Funder
Swedish Energy Agency, P46533-1 and P42034-1
Note

Validerad;2019;Nivå 2;2019-09-09 (johcin)

Available from: 2019-08-13 Created: 2019-08-13 Last updated: 2023-09-05Bibliographically approved
Wagner, K., Häggström, G., Mauerhofer, A. M., Kuba, M., Skoglund, N., Öhman, M. & Hofbauer, H. (2019). Layer formation on K-feldspar in fluidized bed combustion and gasification of bark and chicken manure. Biomass and Bioenergy, 127, Article ID 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 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
Elsevier, 2019
Keywords
Fluidized bed, Layer formation, K-feldspar, Phosphorous, Combustion, DFB steam gasification
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-75063 (URN)10.1016/j.biombioe.2019.05.020 (DOI)000478564300032 ()2-s2.0-85066481346 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-06-27 (johcin)

Available from: 2019-06-27 Created: 2019-06-27 Last updated: 2023-09-05Bibliographically approved
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