Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/4935
標題: 氣泡式流體化床焚化爐中熱傳特性之研究
The study of heat transfer characteristics in bubbling fluidized bed incinerator
作者: 游世達
You, Shr-Da
關鍵字: Bubbling fluidized bed incinerator;氣泡式流體化床焚化爐;Binary bed materials;Heat transfer to immersed spheres;二元床質;熱傳
出版社: 環境工程學系
摘要: 
氣泡式流體化床因其高熱質傳之特性,漸廣為應用於廢棄物焚化處理,但過去基於化工領域之相關研究多以冷模及單一床質為主,而在流體化床焚化爐中,則多操作在高溫及因廢棄物之進料、吸附劑、底灰、床質破碎及燒結等因素而呈現床質複雜之特性下,應用時若未考量上述因子所造成之差異,可能使爐體設計不佳或操作不當而導致二次污染增加,故為了使流體化床焚化爐之技術更為完備,本研究擬以實驗室規模之氣泡式流體化床焚化爐,操作於焚化之溫度下(1000K)藉由添加不同種類(SiO2、Al2O3)、粒徑(545、650、770μm)及添加量(0、10、20wt%)之粒子於基礎床質(545μm-SiO2)中,探討非單一床質對爐內之流體化及熱傳特性之影響,並且配合實際進料燃燒之試驗,以探討非單一床質對燃燒效率之影響。
結果顯示,二元床質流體化床之流體化行為,會隨添加較大或較重床質之含量、粒徑及密度而更接近所添加床質之特性,其中添加量影響最明顯,呈現一幕次關係之趨勢。
在二元床質之hmf方面,因添加氧化鋁砂試程具有較高之體積熱容量而略高於石英砂之試程;另外,因添加較大或較重床質造成Umf之提高,會使熱傳上升段之發生延後,但熱傳上升段之上升率及hmax卻具升高之趨勢,推測原因可能為添加較大或較重之床質會使相同操作氣速下有較高的床區粒子濃度及增加顆粒小尺度之運動。
二元床質的混合效果會隨添加較大或較重之床質含量增加而降低,而造成CO及CxHy之排放濃度明顯提高,另外,實驗結果亦顯示,熱傳係數對於PP燃燒效率之影響並不明顯。

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.
URI: http://hdl.handle.net/11455/4935
Appears in Collections:環境工程學系所

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