| Summary: | 碩士 === 國立中興大學 === 環境工程學系 === 90 === Bubbling fluidized bed was conventionally applied in waste incineration, due to its high heat and mass transfer. However, the previous studies focused on cold model and mono bed material in chemical engineering region mainly. Bubbling fluidized bed incinerator is mostly operated under high temperature and complex bed material due to the natural of feed wastes, sorbent, bottom ash, sinter and particle crack. If the above factors were not considered, it may cause inadequate design or operation and subsequently induce the secondary pollution. Experimental was conducted to investigate the influence of complex bed material towards fluidization and heat transfer characteristics. The evaluated parameters included:(1)various particle (SiO2, Al2O3); (2)size(545,650,770μm), and (3)weight fraction (0,10,20wt%) in basic bed material(545μm-SiO2). PP combustion was also conducted to evaluate the relation of fluidization, heat transfer characteristics and combustion efficiency.
The results indicated that the fluidization behavior of binary bed material fluidized bed was affected by the adding material with its weight fraction, particle size and density. Among them, the weight fraction of additives played the most important role and revealed the tendency of an exponential relation.
The hmf in the binary systems of adding Al2O3 was slightly higher than SiO2 due to its higher volumetric heat capacity. The start of heat transfer rising section was postponed by the raise of Umf. The rising tendency of heat transfer rising section and hmax was increased by the addition of particle with higher density or larger size. It was supposed that the higher density or larger size increase the bed particle packing concentration and movement at the same superficial gas velocity.
The mixing efficiency in binary bed materials were decreased with increased quantity of addition of particle with higher density or larger size. Nevertheless, the influence of heat transfer rate towards combustion efficiency of PP is not apparent.
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