Thermodynamic equilibrium prediction of bed agglomeration tendency in dual fluidized-bed gasification of forest residues

Interactions of Olivine and Silica Sand with Potassium- or Silicon-Rich Agricultural Residues under Combustion, Steam Gasification, and CO2 Gasification

“…Kuba et al also reported that the mass fractions of K in the inner and outer layers formed on olivine are only 0.6 and 0.7, which are significantly lower than that of the layers formed on the quartz sand (23.5 in the inner layer and 6.7 in the outer layer) . This implies that the layers formed on the olivine are more thermally stable . These findings were supported by the experimental work of Grimm et al and Fryda et al, suggesting that olivine significantly reduces the agglomeration by forming an inner layer dominated by Ca compounds instead of K. The study of Kuba et al identified the mechanism of coating layer formation on olivine through a solid–solid substitution reaction between Ca-rich wood ash and olivine particles.…”

“…These findings were supported by the experimental work of Grimm et al and Fryda et al, suggesting that olivine significantly reduces the agglomeration by forming an inner layer dominated by Ca compounds instead of K. The study of Kuba et al identified the mechanism of coating layer formation on olivine through a solid–solid substitution reaction between Ca-rich wood ash and olivine particles. Note that the fuels used in their studies ,,, consisted of a large amount of Ca, which leads to the conclusion that the formation of coating layers on olivine is dominated by the Ca content rather than that of K, which differs from the case that was observed for silica sand when wood-based fuels were used . For instance, when using silica sand as the bed material, the coating layer formation was initiated by a gas-phase reaction of K and the particle surface forming potassium silicates, followed by Ca diffusion into the initial K-rich layer .…”

“…Previous work has predicted that DFB gasification of forest residues with silica sand will lead to the sand being coated with a layer composed of an estimated 20–40 wt % of molten phases, which is likely to induce agglomeration . In contrast, olivine was predicted to be coated with a layer of mostly Ca–Mg-silicates under the same conditions and the molten phases were predicted to account for less than 3 wt % of the coating layer .…”

“…Previous work has predicted that DFB gasification of forest residues with silica sand will lead to the sand being coated with a layer composed of an estimated 20−40 wt % of molten phases, which is likely to induce agglomeration. 27 In contrast, olivine was predicted to be coated with a layer of mostly Ca− Mg-silicates under the same conditions and the molten phases were predicted to account for less than 3 wt % of the coating layer. 27 Kuba et al also reported that the mass fractions of K in the inner and outer layers formed on olivine are only 0.6 and 0.7, which are significantly lower than that of the layers formed on the quartz sand (23.5 in the inner layer and 6.7 in the outer layer).…”

“…27 In contrast, olivine was predicted to be coated with a layer of mostly Ca− Mg-silicates under the same conditions and the molten phases were predicted to account for less than 3 wt % of the coating layer. 27 Kuba et al also reported that the mass fractions of K in the inner and outer layers formed on olivine are only 0.6 and 0.7, which are significantly lower than that of the layers formed on the quartz sand (23.5 in the inner layer and 6.7 in the outer layer). 28 This implies that the layers formed on the olivine are more thermally stable.…”