umu.sePublications
Change search
Link to record
Permanent link

Direct link
BETA
Backman, Rainer
Alternative names
Publications (10 of 61) Show all publications
Hagman, H., Bostrom, D., Lundberg, M. & Backman, R. (2019). Alloy degradation in a co-firing biomass CFB vortex finder application at 880 degrees C. Corrosion Science, 150, 136-150
Open this publication in new window or tab >>Alloy degradation in a co-firing biomass CFB vortex finder application at 880 degrees C
2019 (English)In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 150, p. 136-150Article in journal (Refereed) Published
Abstract [en]

Mechanisms of alloy degradation in a fireside N-S-O-C-H-Cl-Na-K atmosphere at 880 degrees C were elucidated using SEM-EDS, chemical equilibrium calculations, and XRD. Alloys 310S, 800H/HT, and 600 were studied after 0, 8000, and 16,000 h exposure in a boiler co-firing biomass waste. For 310S and 800H/HT it was shown that nitrogen formed internal Cr nitrides lowering the Cr activity and inhibiting internal alloy Cr permeation, and that NaCl and Na2SO4 reacted with Cr oxide to form chromate and to accelerate the S and the Cl pickup. Alloy 600 showed no nitride or major chromate formation.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Na, K, Cl, O-2, CO, CO2, HCl, SO2, NH3, N-2, Nitride, Carbide, Sulfide, Oxide, Chloride, Volatilization, Vortex finder, CFB boiler, High-temperature corrosion, Alloy 310S, Alloy 800H/HT, Alloy 600, Co-combustion
National Category
Corrosion Engineering
Identifiers
urn:nbn:se:umu:diva-157937 (URN)10.1016/j.corsci.2019.01.038 (DOI)000462108000014 ()
Available from: 2019-04-18 Created: 2019-04-18 Last updated: 2019-04-18Bibliographically approved
Strandberg, A., Skoglund, N., Thyrel, M., Lestander, T. A., Broström, M. & Backman, R. (2019). Time-Resolved Study of Silicate Slag Formation During Combustion of Wheat Straw Pellets. Energy & Fuels, 33(3), 2308-2318
Open this publication in new window or tab >>Time-Resolved Study of Silicate Slag Formation During Combustion of Wheat Straw Pellets
Show others...
2019 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 33, no 3, p. 2308-2318Article in journal (Refereed) Published
Abstract [en]

Ash formation during single-fuel pellet combustion of wheat straw at 700 and 1000 °C was studied throughout fuel conversion by quench cooling and analysis at different char conversion degrees. The combination of X-ray microtomography analysis and scanning electronic microscopy with energy-dispersive X-ray spectroscopy showed that ash accumulated in rigid net structures at 700 °C with streaks or small beads surrounding the char, and the pellet mostly maintained its size during the entire fuel conversion. At 1000 °C, the ash formed high-density melts that developed into bubbles on the surface. As the conversion proceeded, these bubbles grew in size and covered parts of the active char surface area, but without entirely blocking the gas transport. The successive char conversion dissolved increasing amounts of calcium in the potassium silicate melts, probably causing differences in the release of potassium to the gas phase. Similarities were found with slag from a combustion experiment in a domestic boiler, with regard to relative composition and estimated and apparent viscosity of the slag. Complete char encapsulation by ash layers limiting char burnout was not found at the single pellet level, nor to any greater extent from the experiment performed in a small domestic boiler.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
National Category
Inorganic Chemistry Other Environmental Engineering
Identifiers
urn:nbn:se:umu:diva-157725 (URN)10.1021/acs.energyfuels.8b04294 (DOI)000462260600064 ()
Funder
Swedish Research Council, 2014-5041Bio4Energy
Available from: 2019-04-02 Created: 2019-04-02 Last updated: 2019-04-12Bibliographically approved
Strandberg, A., Skoglund, N., Thyrel, M., Lestander, T. A., Broström, M. & Backman, R. (2019). Wheat straw pellet combustion – characterization with X-ray micro-tomography and SEM-EDS analysis. In: : . Paper presented at World Sustainable Energy Days, 28 February, 2019, Wels, Austria.
Open this publication in new window or tab >>Wheat straw pellet combustion – characterization with X-ray micro-tomography and SEM-EDS analysis
Show others...
2019 (English)Conference paper, Oral presentation with published abstract (Refereed)
National Category
Energy Engineering
Identifiers
urn:nbn:se:umu:diva-157286 (URN)
Conference
World Sustainable Energy Days, 28 February, 2019, Wels, Austria
Funder
Swedish Research Council, 2014-5041Swedish Research Council Formas, 2017-01613
Available from: 2019-03-13 Created: 2019-03-13 Last updated: 2019-03-19
Broström, M., Holmgren, P. & Backman, R. (2018). Ash fractionation and slag formation during entrained flow biomass gasification. In: : . Paper presented at The 27th International Conference on the Impacts of Fuel Quality on Power Production and the Environment, Lake Louise, Alberta, Canada, September 24-28 2018..
Open this publication in new window or tab >>Ash fractionation and slag formation during entrained flow biomass gasification
2018 (English)Conference paper, Oral presentation only (Other academic)
National Category
Chemical Engineering Bioenergy
Identifiers
urn:nbn:se:umu:diva-152042 (URN)
Conference
The 27th International Conference on the Impacts of Fuel Quality on Power Production and the Environment, Lake Louise, Alberta, Canada, September 24-28 2018.
Available from: 2018-09-25 Created: 2018-09-25 Last updated: 2018-11-22Bibliographically approved
Strandberg, A., Thyrel, M., Skoglund, N., Lestander, T. A., Broström, M. & Backman, R. (2018). Biomass pellet combustion: cavities and ash formation characterized by synchrotron X-ray micro-tomography. Fuel processing technology, 176, 211-220
Open this publication in new window or tab >>Biomass pellet combustion: cavities and ash formation characterized by synchrotron X-ray micro-tomography
Show others...
2018 (English)In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 176, p. 211-220Article in journal (Refereed) Published
Abstract [en]

Ash formation during thermochemical conversion of biomass-based pellets influences both char conversion rates and ash-related operational problems. The objective of the present study was to provide detailed insights into changes in fuel and ash properties during fuel conversion. Pellets of poplar wood and wheat straw were used as model biofuels, representing vastly different compositions of ash-forming elements. Pellet samples at different char conversion phases were analyzed by synchrotron-based 3D X-ray micro-tomography, to map and visualize the development of cracks, internal cavities, and ash layers during conversion. The analysis of ash layers was complemented by scanning electron microscopy combined with energy-dispersive X-ray spectroscopy. The results provide new insights into how large cracks and internal cavities are developed already during devolatilization, for example, the poplar wood pellets had a 64% void fraction after the devolatilization stage. As expected, there were large variations between the ash layer properties for the two fuels. A porous, low density, and calcium-rich ash was formed from the poplar fuel, whereas the wheat straw ash was a high-density silicate melt that developed into bubbles on the surface. As the conversion proceeded, the wheat straw ash covered parts of the active char surface area, but without blocking the gas transport.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
ash composition, pellet, thermochemical conversion, wheat straw, poplar, SEM-EDS
National Category
Chemical Process Engineering Bioenergy
Identifiers
urn:nbn:se:umu:diva-146673 (URN)10.1016/j.fuproc.2018.03.023 (DOI)
Available from: 2018-04-17 Created: 2018-04-17 Last updated: 2018-06-09Bibliographically approved
Holmgren, P., Broström, M. & Backman, R. (2018). Slag Formation during Entrained Flow Gasification: Silicon Rich Grass Fuel with KHCO3 Additive. Energy & Fuels, 32(10), 10720-10726
Open this publication in new window or tab >>Slag Formation during Entrained Flow Gasification: Silicon Rich Grass Fuel with KHCO3 Additive
2018 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 32, no 10, p. 10720-10726Article in journal (Refereed) Published
Abstract [en]

Prediction of ash particle adherence to walls, melting, and flow properties are important for successful operation of slagging entrained flow gasifiers. In the present study, silicon-rich reed canary grass was gasified at 1000 and 1200 °C with solid KHCO3 added at 0, 1, or 5 wt % to evaluate the impact and efficiency of the dry mixed additive on slag properties. The fuel particles collided with an angled flat impact probe inside the hot reactor, constructed to allow for particle image velocimetry close to the surface of the probe. Ash deposit layer buildup was studied in situ as well as ash particle shape, size, and velocity as they impacted on the probe surface. The ash deposits were analyzed using scanning electron microscopy–energy-dispersive X-ray spectroscopy, giving detailed information on morphology and elemental composition. Results were compared to thermodynamic equilibrium calculations for phase composition and viscosity. The experimental observations (slag melting, flow properties, and composition) were in good qualitative agreement with the theoretical predictions. Accordingly, at 1000 °C, no or partial melts were observed depending upon the potassium/silicon ratio; instead, high amounts of additive and a temperature of at least 1200 °C were needed to create a flowing melt.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
National Category
Energy Engineering Other Chemical Engineering
Identifiers
urn:nbn:se:umu:diva-151688 (URN)10.1021/acs.energyfuels.8b02545 (DOI)000448087000068 ()2-s2.0-85053900505 (Scopus ID)
Available from: 2018-09-10 Created: 2018-09-10 Last updated: 2018-11-30Bibliographically 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
Show others...
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
Show others...
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
Strandberg, A., Thyrel, M., Rudolfsson, M., Lestander, T. A., Backman, R., Skoglund, N. & Broström, M. (2017). Char conversion characterizedby synchrotron based X-ray micro-tomograhy and SEM-EDS analysis. In: EUBCE 2017 – 25th European Biomass Conference and Exhibition, 12-15 June 2017, Stockholm, Sweden: . Paper presented at EUBCE 2017 – 25th European Biomass Conference and Exhibition, 12-15 June 2017, Stockholm, Sweden.
Open this publication in new window or tab >>Char conversion characterizedby synchrotron based X-ray micro-tomograhy and SEM-EDS analysis
Show others...
2017 (English)In: EUBCE 2017 – 25th European Biomass Conference and Exhibition, 12-15 June 2017, Stockholm, Sweden, 2017Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Fuel and ash properties were studied during fuel conversion by careful examination of char samples at different degrees of char oxidation. Two types of lignocellulosic pellets with different compositions of ash forming elements were used: poplar and straw from wheat. The charred pellets were investigated by synchrotron-based X-ray micro-tomography to create 3D images of the development of cracks, internal cavities, and ash layers during conversion.  Furthermore, SEM-EDS was used to for detailed chemical and morphological information of the ash layers formed. The pore development during pellet conversion was found to deviate from what has previously been described for the structure of solid wood particles. Large cracks and internal cavities were formed extensively already during devolatilization. For poplar, no mobility of the ash forming elements were observed as the burnout proceeded. Ash layer properties varied between the two fuels: poplar formed a porous, permeable, low density and Ca rich ash, whereas wheat straw ash accumulated on the surface in the form of high density melt that develop into bubbles on the surface. As the conversion proceeded, the ash layer covered more of the active char surface area, but without totally blocking the gas transport.

Keywords
chemical composition, pellet, thermochemical conversion, wheat straw, poplar
National Category
Energy Engineering Analytical Chemistry
Identifiers
urn:nbn:se:umu:diva-136274 (URN)10.5071/25thEUBCE2017-2BO.14.5 (DOI)978-88-89407-17-2 (ISBN)
Conference
EUBCE 2017 – 25th European Biomass Conference and Exhibition, 12-15 June 2017, Stockholm, Sweden
Funder
Bio4Energy
Available from: 2017-06-15 Created: 2017-06-15 Last updated: 2018-06-09
Holmgren, P., Broström, M. & Backman, R. (2017). Slag formation during entrained flow gasification. Part 1: Calcium rich bark fuel. In: : . Paper presented at Nordic Flame Days 2017, Stockholm, Sweden, October 10-11, 2017. Stockholm, Sweden
Open this publication in new window or tab >>Slag formation during entrained flow gasification. Part 1: Calcium rich bark fuel
2017 (English)Conference paper, Oral presentation only (Other academic)
Place, publisher, year, edition, pages
Stockholm, Sweden: , 2017
National Category
Chemical Engineering
Identifiers
urn:nbn:se:umu:diva-146668 (URN)
Conference
Nordic Flame Days 2017, Stockholm, Sweden, October 10-11, 2017
Available from: 2018-04-16 Created: 2018-04-16 Last updated: 2019-06-25Bibliographically approved
Organisations

Search in DiVA

Show all publications