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研究生:洪朝陽
研究生(外文):Hung Chao Yang
論文名稱:流體化床焚化逸失及其危害風險研究
論文名稱(外文):Elutriation from fluidized bed incineration and the hazardous risk research
指導教授:章裕民章裕民引用關係
指導教授(外文):Yu-Min Chang
學位類別:碩士
校院名稱:國立臺北科技大學
系所名稱:土木與防災技術研究所
學門:工程學門
學類:土木工程學類
論文種類:學術論文
論文出版年:1999
畢業學年度:87
語文別:中文
論文頁數:101
中文關鍵詞:流體化床焚化逸失
外文關鍵詞:fluidized bedincinerationelutriation
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以焚化技術來處理廢棄物雖然不是唯一且最佳的方式,但是由於焚化處理的良好減積效果,對於地狹人稠的我國來說卻不失為一值得發展的技術。而流體化床技術自1926年商業化以來,不僅可應用在傳統產業領域,在能源科技及廢棄物處理領域裡皆具有深厚之發展潛力。緣此,本研究之主要研究目的為:
1. 配合流體化床及焚化原理,利用實驗所得到的數據以探討焚化時逸失量之變化情形。
2. 研究流體化床中高溫焚化時影響逸失率的原因,及其量化效應程度。
本研究藉由自行設計的小型實驗級流體化床焚化爐,以稻殼為進料,在500±20°C定溫下進行焚化逸失現象實驗。所採用之爐床內徑為20cm,爐高約1.5m。使用河砂做為流化介質,由終端速度大於氣體表面速度的粗粒子所組成(99.9%以上),其平均粒徑為573mm。實驗操作之氣速範圍在0.200~0.325m/s之間(在500±20°C定溫下)。除了量測不同操作氣速下之逸失現象與分析逸失物質的粒徑分佈外,亦針對流體化床焚化爐逸失現象對於環境與健康問題及成本增加問題等進行探討,作為將來設計與操作時的參考,降低因粒子逸失所造成的危害風險。
實驗結果顯示流化介質的逸失率會隨著操作氣速提高而增加,對於由粗粒子所組成的爐床,其產生的逸失量要比推估值來得低。焚化操作時,由於稻殼燃燒後的飛灰密度低,在相同的乾舷區高度下,飛灰為主要逸失物質。在固定的乾舷區高度下,提高操作氣速會減少焚化時的氣體停留時間,導致焚化效率的降低,從實驗結果發現飛灰的灼燒損失量會隨著氣速提高而增加,且與氣速有正次方的關係。基此,綜合本研究結果可得知:
1. 理論上只有當粒子終端速度小於操作氣速時才會被逸失,但實際操作時仍發現有終端速度大於氣速的粒子被 帶出系統。
2. 當採用組成皆屬於粗粒子的砂作為流化介質時,對於砂而言可以有效地避免其逸失。
3. 焚化時稻殼燃燒後的灰渣亦可作為流化介質,但因為其密度較小,容易被氣流帶出系統,而成為焚化操作時 的主要逸失物質。
4. 穩定操作條件(爐床壓降與爐床溫度穩定)下,在進料速率6±1kg/hr,操作溫度500±20°C,改變操作氣速 得到與總逸失率的關係為:
ln E = 26.105u - 13.921(R2=0.9820)
E:總逸失速率(kg/m2s)
u:表面氣體速度(m/s)
5. 從風險危害的初步評估可知,流體化床焚化逸失所造成的問題,除了可能增加焚化未燃物(包括可能致癌物 與重金屬等)的逸失量,致影響其周界的空氣品質外,亦會增加本身的操作成本。如以內徑5m的商用中型流 體化床焚化爐為例,不考慮除塵設備額外的O&M成本下,當總逸失量減少20%時,粗略估算每年可以節省約 375,282元的砂補充費用。

目 錄
摘 要................................................................................................................................i
誌 謝..............................................................................................................................iii
目 錄..............................................................................................................................iv
表目錄............................................................................................................................vi
圖目錄............................................................................................................................viii
第一章 緒論...................................................................................................................1
1-1 流體化床焚化技術之定位................................................................................1
1-2 流體化床焚化爐概說.........................................................................................2
1-3 研究目的...............................................................................................................5
1-4 研究內容...............................................................................................................5
第二章 理論背景與文獻回顧......................................................................................6
2-1 流體化基本原理..................................................................................................6
2-2 載送與逸失現象..................................................................................................8
2-2-1 逸失分離高度(TDH)................................................................................9
2-2-2 終端速度........................................................................................................10
2-2-3 最小流體化速度...........................................................................................12
2-3 載送之基本現象................................................................................................13
2-3-1 乾舷區內之粒子運動行為..........................................................................15
2-4 粒子逸失機制與模式........................................................................................17
2-4-1 逸失機制.........................................................................................................17
2-4-2 逸失模式.........................................................................................................19
2-5 影響逸失之因素..................................................................................................22
2-6 數學關係式..........................................................................................................23
2-7 國內外研究情況.................................................................................................26
2-8 流體化床焚化爐應用現況................................................................................29
第三章 研究內容及方法..............................................................................................40
3-1 研究內容...............................................................................................................40
3-2 研究方法...............................................................................................................40
3-3 重要實驗設備......................................................................................................46
3-4 研究步驟...............................................................................................................48
第四章 結果與討論.......................................................................................................50
4-1 TDH之確認..........................................................................................................50
4-2 冷態操作下之逸失現象.....................................................................................52
4-3 熱態操作下之逸失現象.....................................................................................71
4-4 焚化逸失率之推估式..........................................................................................83
4-5 冷熱爐逸失現象之比較......................................................................................84
第五章 逸失危害風險評析...........................................................................................89
第六章 結論與建議........................................................................................................95
參考文獻...........................................................................................................................97
附錄A:溫度記錄設備(包括軟體)資料....................................................................I
附錄B:相關實驗設備之照片..................................................................................XXXI
附錄C:冷態逸失率與風速之關係式...........................................................................XL
附錄D:冷熱條件下之總逸失率與其他模式推估值之比較................................XLII
符號彙編
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