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

Valizadeh, Ali; Skoglund, Nils; Forsberg, Fredrik; Lycksam, Henrik; Öhman, Marcus

doi:10.1016/j.fuel.2023.127707

Cited by 3 publications

(9 citation statements)

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“…As the bed materials undergo structural changes throughout the combustion process, distinct regions emerge in the bed particles, each exhibiting unique visual characteristics and chemical composition. The standard thresholding procedure was employed for the identification of these regions . This involved visually comparing XMT images with scanning electron microscopy (SEM) images to select appropriate X-ray attenuation ranges for each region.…”

Section: Materials and Methodsmentioning

confidence: 99%

“…To determine the average thickness of the bed particle layer for each bed sample, a similar segmentation procedure was employed. The bed particle layer identified in each bed particle was then examined using the thickness measurement toolbox in Dragonfly software. , More details on the segmentation of different regions in XMT images, as well as the methodologies used for calculating layer thickness and volume fractions, could be found elsewhere …”

Section: Materials and Methodsmentioning

confidence: 99%

“…The standard thresholding procedure was employed for the identification of these regions. 25 This involved visually comparing XMT images with scanning electron microscopy (SEM) images to select appropriate X-ray attenuation ranges for each region. Subsequently, the particles were segmented into these identified regions.…”

Section: X-ray Microtomography Analysismentioning

confidence: 99%

“…The bed particle layer identified in each bed particle was then examined using the thickness measurement toolbox in Dragonfly software. 25,27 More details on the segmentation of different regions in XMT images, as well as the methodologies used for calculating layer thickness and volume fractions, could be found elsewhere. 25 1 and 2 depict the changes in the shapes of typical sand and rock ilmenite bed particles throughout the exposure.…”

Section: X-ray Microtomography Analysismentioning

confidence: 99%

“…The calculation process is given in more detail elsewhere. 25 With the volume (V p ) and surface area (A p ) of the bed particles determined, the sphericity was calculated using the following equation 31 and subsequently averaged for each bed sample.…”

Section: X-ray Microtomography Analysismentioning

confidence: 99%

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Role of Particle Geometry on the Structural Integrity of Sand and Rock Ilmenite Used as Oxygen Carrier in Combustion of Woody Biomass

Valizadeh,

Faust,

Skoglund

et al. 2024

Energy Fuels

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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 MW th 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.

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Section: Materials and Methodsmentioning

confidence: 99%