Journal of the Japan Institute of Energy

In order to reduce emission of unburnt gas (CO, hydrocarbon) from fluidized bed incinerators, porous alumina was used as a bed material instead of conventional bed material (sand). Polyethylene pellets were burnt in a bench-scale bubbling fluidized bed incinerator. Porous bed material was found to be effective not only for the reduction of unburnt gas emission but also thermal-NOx emission. The reduction of thermal-NOx was explained by the suppression of flame combustion in the freeboard due to increased combustion in the dense bed and enhanced horizontal mixing of carbonaceous material. The horizontal concentration profile in the freeboard became uniform when the porous particle was employed. The above results were explained by the capacitance effect (hydrocarbon capture by pore) of the porous material.

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The standard analysis of coal by X ray diffraction (STAC-XRD), including evaluation of the number of aromatic layers in a stack (n), the average number of n (n_(ave)), the average distance between two aromatic layers (d₀₀₂), and stacking index (SI), has been applied to several types of coals deashed and solvent-treated with hexane or methanol. Little influence of deashing was found on the distribution of n, as well as n_(ave), d002, and SI values. On the other hand, solvent treatment brought about almost the common changes for the coals employed, i.e., increase in n_(ave), and decrease in d002 and SI. These changes were explained owing to partial destruction of the loose stacking of the aliphatic layers attached to aromatic rings with the solvent treatment. The presence of the stacking of aliphatic carbons was suggested by taking into account a broad peak overlapped upon the 002 reflection peak due to aromatic carbons.

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