臺灣博碩士論文加值系統

本研究主旨在研究反應器設計與產率間的關係。研究中的理論產量係以TGA熱分析得到先趨物在實驗溫度下的重量損失率推求而得，此值可計算在反應器微粒收集器中濾紙所收集到的粉粒體產率，及器壁上因熱泳沉積及其它氣膠沉積機制造成的器壁沉積率。實驗係以已知重量的鋁箔紙貼覆在反應器各部份的內壁上，由實驗前後的鋁箔紙重量差，實際量測反應器各部位的沉積量與相對比率，來檢視各部位的沈積率，並探討沈積原因後，在反應器設計上予以改善，再進行實驗，比較改善前與改善後之產率。
實驗變數包括霧化器至預熱乾燥區以前的氣膠輸送管線的設計、反應器加溫區段管壁絕熱包覆的效果、高溫爐爐管在爐末端延伸的長度、不同的高溫爐溫度(600和800℃)、高溫爐末端熱氣膠以套流包覆來抑制熱泳沉積的效果，和不同的套流比及溫度對產率的影響。實驗結果顯示，因管件方向設計不良，霧滴的重力沈降可能造成高達30％的沈積，熱泳沈積在實驗中600℃、800℃下，在8-13%範圍。本實驗室反應器經改良後產率由改良前的50%，提昇至80%左右。

Thermophoresis was suspected to be the prime reason for the significant loss of product powders in spray pyrolysis aerosol reactors. However, there is no published experimental evidence supporting this speculation yet. To answer this question, a lab-scale spray pyrolysis reactor capable of producing 1-2 grams per hour was designed and constructed. Preliminary runs were carried out to locate where particle losses occur throughout the reactor. The results showed particle losses at locations including the transport tube section between the ultrasonic generator and the diffusion drying section, flanges connecting reactor tubes, and the transport tube between downstream of the higher temperature pyrolysis furnace and the particle collection device. Possible deposition mechanisms at each of these locations were suggested and necessary correction measures were comprehended.
Quantitative determination of particle loss was made by directly collecting particles with pre-weighted aluminum foils covered on inside walls of the reactor at each of these locations. Thermogravimetric analysis was used to determine the actual amount of powders resulted from precursor solution consumed in each run. This result allows the calculation of particle deposition at each location and actual product yield on filter. Experiments were also conducted to examine the effect of using clean sheath gas around the hot aerosol out from the furnace to suppress thermophoretic deposition. After modifications, product yield increased significantly from 50% to 80%. Thermophoresis was found no the only relevant deposition mechanism in this type of system. When the liquid spray transport tube was not properly designed, a significant loss of the liquid droplets of several microns in size due to gravitational settling or inertial impaction may result.

書名頁
論文口試委員審定書
授權書
中文摘要……………………………………………………...…………….I
英文摘要…………...…………………………………………..………….II
誌謝………………………………….……………..……………………..IV
目錄…….…………..……………………………………..……………….V
表目錄……………..….…………………………………………………VII
圖目錄……………..…………….……………………………………...VIII
符號說明………………………….……………………………………….X
第一章 緒論…………………………..……..………………………….1
第二章 文獻回顧……………………………..…………………….…..4
2.1氣膠基本沈積機制………………………………………...…….4
2.1.1重力沈降………………………………………………….4
2.1.2 擴散……………..……..…………………………………6
2.1.3 慣性衝擊………...……………………………………….8
2.1.4 熱泳動……………………………….………………….10
2.1.5 膠結………………………………….………………….13
2.2 噴霧熱分解粉粒體製程簡介.…………………………………14
2.2.1 先驅物溶液霧化………………..………………………14
2.2.2 先驅物溶液霧滴乾燥………..….…………..………….15
2.2.3 先驅物微粒裂解反應……………………….………….15
2.2.4 高溫微粒產物的冷卻輸送…………...………………...16
2.2.5 產物微粒由氣相分離…………………………………..16
2.2.6 抑制噴霧熱分解中熱泳沈積的過去研究………..……16
第三章 無塵套流抑制熱泳沉積原理………………………………….19
第四章 實驗方法……………………………………………………….23
4.1 實驗藥品及器材……………...……………………………..…23
4.2 分析儀器……………………………………………………….23
4.3 實驗系統與操作…………………………………………...…..24
4.3.1實驗系統……………………………..………………….24
4.3.2實驗方法與步驟……………………………………..….24
4.3.2.1 先趨物溶液配製………………………………25
4.3.2.2 反應器操作步驟………………………………25
4.4可視化流場之觀察……………………………………………..26
第五章 結果與討論………………………………………..………….29
5.1 先驅物熱重損失率測定及測試微粒結構、粒徑測量………..29
5.2 法蘭包覆是否妥當……………………………………………..29
5.3 霧滴輸送管線的影響…………………………………………..35
5.4 高溫爐出口處沉積的改善……...………………………40
5.5 套流對冷卻輸送段沉積現象的改善…………………………..43
5.6 可視化流場觀察無塵套流對抑制微粒沉積的定性結果……..53
第六章 結論……………………………………………..…………….58
參考文獻…………….…………………...……………………………….60
附錄A 微粒在標準狀態下(1 atm, 20℃)的性質……...……………….63
簡歷……………………………………………………………………….64

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