Role of surface morphology in bed particle layer formation on quartz bed particles in fluidized bed combustion of woody biomass

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

doi:10.1016/j.fuel.2023.129702

Cited by 2 publications

(4 citation statements)

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“…In both types of bed particles, it was found that a significant number of cracks originated from or were connected to the concave areas on the bed particle surface (Figures and ). This is in line with previous findings on crack development in bed particles utilized in FB systems, which indicates a consistent pattern in the behavior of crack development in relation to the bed particles’ surface geometry …”

Section: Resultssupporting

confidence: 92%

“…In contrast, the bed particle layer on rock ilmenite particles appeared to be more uniform and covered almost the entire surface of the particles (Figure ). The observed variation in layer formation on convex and concave surfaces of the bed particles aligns with findings reported in previous research. ,− …”

Section: Resultssupporting

confidence: 91%

“…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 efficiency of fluidized bed combustion (FBC) systems and their economic viability depend significantly on the choice of bed material. Studies on different bed materials have indicated that the interaction of the fuel-derived ash compounds with bed particles is not solely affected by the changes in the chemical composition of the bed material but also by the changes in surface morphologies of the bed particle. − For instance, a recent study focusing on ilmenite revealed that the Ca-rich layer tends to form more readily on the convex regions of the particle . This phenomenon leaves the concave regions without a Ca-protection layer, leading to the further depletion of iron from the bed particle core through these areas .…”

Section: Introductionmentioning

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: Resultssupporting

confidence: 92%