JETI

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Abstract

This study has concentrated on the affirmation of agglomeration in some selected biomass fuels - miscanthus, willow, and white wood during their combustion processes. Gooch crucible was used as the combustion chamber. During the combustion processes, agglomerates were formed in the combustion chamber at 750 oC and 802 oC under the atmospheric pressure. This was attributed to the formation of eutectic compounds in the form of alkali-silicates (K-silicates or Na-silicates). The eutectic compound has a lower melting temperature than the melting temperature of either the alkali metals or the silica from the bed materials (sand). It therefore melts abruptly in the bed and formed lumps in form of agglomerates. Post combustion analyses - scanning electron microscopy and energy dispersive x-ray spectroscopy (SEM and EDX) established agglomerates formation during the combustion processes of these selected problematic biomass fuels. EDX results indicated that the interior of the agglomerates was dominated with Si from the sand while the exterior were preponderated with alkali metals, K, and Na from the biomass fuels ash. Other trace elements present in the agglomerates are Al, Ca, Cl, Fe, P, and Mg. With the addition of 10% additive (kaolin) Al2Si2O5(OH)4 to the bed materials and the combustion processes repeated under the same operating conditions, no agglomerate was formed at 750 oC and 802 oC. The results have confirmed that, kaolin is a very reliable additive to reduce agglomeration during biomass fuel combustion for heat generation (HG) or combine heat and power generation (CHPG). This is also applicable to fluidized bed combustion (FBC).

References

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