Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/4945
標題: 以流體化床控制焚化廢氣中污染物之研究
Control of Incinerator Pollutants by a Fluidized Bed Reactor
作者: 蔣博欽
Chiang, Bo-Chin
關鍵字: fluidized bed reactor
流體化床反應器
incineration
particulate
organics
heavy metals
acid gases
activated carbon
焚化
粒狀物
有機物
重金屬
酸性氣體
活性碳
出版社: 環境工程學系
摘要: 本研究主要探討以流體化床反應器控制煙道氣中粒狀污染物,並串聯袋式集塵器,探討不同流體化操作條件下,對粒狀污染物包括模擬飛灰及實際燃燒產生飛灰的控制效率,並由各操作條件的影響探討流化床除塵的控制機制。之後再評估流體化吸附床串聯袋式集塵器組合,應用至對各種不同性質的焚化二次污染物包括有機物污染物、重金屬污染物及酸性氣體的個別或同時去除,最後吸附重金屬之底灰部分,將利用熱處理的方式使其穩定化。 在比較活性碳基礎床質與模擬飛灰混合床質之淘失及流化床濾除模擬飛灰之實驗時,結果顯示B/C粒子群混合床質的淘失現象並不適用於流化床過濾粒狀物的結果。25℃常溫下,操作氣速及靜置床高的增加有助於模擬飛灰的濾除,且以慣性衝擊為主要濾除機制,高溫(200℃)環境除慣性衝擊機制外,亦加強了擴散機制,且床溫效應對模擬飛灰去除效率的影響遠大於靜置床高及操作氣速的改變。對於次微米(submicron)模擬飛灰流化床具有93.2%~99.4%之去除效率,且高溫由於擴散機制的作用更利於次微米微粒的控制。由於流化床去除實際燃燒產生飛灰的效率,明顯低於對模擬飛灰的去除效率,因此推測飛灰之性質如化學組成亦是影響流化床除粒狀物的主因。流體化床串聯袋式集塵器此組合對粒狀物之去除效率多趨近完全濾除。 將流體化吸附床串聯袋式集塵器應用至焚化系統的結果指出,流體化吸附床在除酸的同時,亦可同時對有機污染物、重金屬氣膠及粒狀污染物進行控制。低濃度KOH浸泡處理過之活性碳有助於氣相PAHs的控制。而吸附床溫度的提高有助於化學吸附為主之重金屬的吸附。最後,利用高溫熱處理方式來處理焚化過後所生成含重金屬之固體吸附劑是有效且可行的,尤其是對重金屬Pb而言,而高溫熱處理溫度的影響較熱處理時間來的明顯且重要。
The major objective of the study focuses on the control of particulates in flue gas. The fluidized bed reactor was employed in a laboratory-scale fluidized bed incinerator to demonstrate the performance of the fluidized bed reactor for removal of particulates simulated or generated from incineration at various fluidized operating conditions, and then the control mechanisms of particulates filtered by fluidized bed were studied. Subsequently, a fluidized bed adsorber integrated with a fabric filter applied to control the incinerator pollutants contained organic, heavy metal and acid gas emissions individually and simultaneously during incineration process were evaluated. Heat treatment of incinerator retired sorbents containing heavy metals could increase the stability of metals was also identified. While comparing the results of the elutriation of group B-C mixtures (activated carbon and simulated fly ash) with the removal of simulated fly ash using a fluidized bed reactor, the results indicate that the elutriation mechanism is not similar to the filtration mechanism. Higher operating velocities and fixed bed heights can enhance the removal of simulated fly ash and inertial impaction is the main mechanism when the fluidized bed is controlled at room temperature (25℃). Besides inertial impaction, diffusion mechanism also occurs when the fluidized bed is controlled at high temperature (200℃) and the temperature effect covers the effects of fixed bed height and operating velocity. On the other hand, the fluidized bed has the ability to filter 93.2% to 99.4% submicron simulated fly ash, and higher temperature is a favorable condition due to diffusion mechanism. Because of the removal efficiency of fly ash generated from incineration is much lower than that of simulated fly ash; it is supposed that characteristics of fly such as chemical composition are also the major factors when using a fluidized bed to filter particulates. A novel air pollution control devices (APCDs) combination, the fluidized bed adsorber integrated with a fabric filter, can control organics, heavy metals and acid gases simultaneously. Activated carbon after immersing with KOH solution is benefit to adsorb gaseous phase PAHs, and higher adsorption temperatures can increase the removal efficiencies of metals due to chemical adsorption. Heat treatment, serving as a control technique for heavy metals on retired sorbents, is effective and feasible, especially for Pb, and the influence of treatment temperature is more important than treatment time.
URI: http://hdl.handle.net/11455/4945
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