戴奧辛類化合物排放過程中之傳輸流佈與相性轉化特性

Characteristics of Phase Conversion and Transformation Fate for PCDD/Fs from the Emission Sources of Environmental Releases

王雅馨(Ya Hsin, Wang)

指導教授 ： 林傑 博士

國立屏東科技大學/工學院/環境工程與科學系所/博士(2009年)

https://doi.org/10.6346/NPUST.2009.00255

摘要

戴奧辛（polychlorinated dibenzo-p-dioxins/dibenzofurans, PCDD/Fs）類化合物於排放過程中可存在於氣體中，也可被結合於微粒物質中，係以氣相及固相之方式存在。而不同排放源因使用不同的操作及控制設備、不同的操作程序與條件，對於PCDD/Fs之生成與破壞皆會有不同程度之影響。本研究針對南部某座都市廢棄物焚化爐（Municipal solid waste incinerator, MSWI）空氣污染防制設備（Air pollution control devices, APCDs）前排放廢氣、煙道、濾袋灰及儲坑飛灰與二級鋁冶煉廠（Secondary aluminum smelter, Secondary ALS）煙道及儲坑飛灰進行PCDD/Fs之採樣分析，並以實驗室Packed Bed Reacter模擬袋式集塵器濾袋灰在前驅物效應及催化效應下PCDD/Fs相性轉化情形，最後並以Fugacity模擬PCDD/Fs傳輸流佈。
焚化爐中隨著活性碳噴注量自10 kg/h增加至17 kg/h時，煙道中PCDD/Fs I-TEQ濃度自0.129 ng I-TEQ/Nm3下降至0.0290 ng I-TEQ/Nm3，PCDD/Fs去除率可達99 %以上。袋式集塵器中不同chamber及濾袋位置上採集之濾袋灰PCDD/Fs含量介於105~148 ng/g，高於儲坑飛灰PCDD/Fs含量7.58 ng/g。由袋式集塵器中PCDD/Fs之質量平衡計算結果，濾袋灰佔83.9 %約為儲坑飛灰之6倍，顯示濾袋灰為PCDD/Fs之重要貢獻來源。因此建議飛灰之管制層面應納入濾袋灰及濾袋之妥善處理。
在實驗室Packed Bed系統模擬試驗方面，濾袋灰經模擬袋式集塵器溫度160 °C加熱後，PCDD/Fs總生成量由605 ng增加至1634 ng。水氣對PCDD/Fs為生成作用且以Flue gas生成量較高。HgCl2對整體PCDD/Fs生成量大幅上升約4倍且主要的生成在於Residue，顯示溫度、水氣、PAHs及氯化金屬皆扮演前驅物及催化PCDD/Fs之形成角色。
二級鋁冶煉廠煙道排放及工作場所空氣中總PCDD/Fs濃度分別為周界大氣之103及3.5倍，經以micro environment觀念利用Fugacity-Level III模擬二級鋁冶煉廠自煙道排放PCDD/Fs至工作場所及周界空氣中之濃度，工作場所空氣實測值及經Fugacity模擬值、周界大氣實測值及經Fugacity模擬值，在PCDD/Fs濃度方面實測值及模擬值分別相差4及5.8倍，PCDD/Fs I-TEQ濃度則分別相差3.4倍。利用Fugacity模式模擬自煙道排放至微環境之濃度結果可知，模擬結果可作為輔助實際採樣及協助污染源鑑定之初步判定。

關鍵字

戴奧辛 ； 焚化爐 ； 二級鋁冶煉廠 ； 袋式集塵器 ； 活性碳噴注 ； 濾袋灰 ； 多介質傳輸模式

並列摘要

Polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) can exist in the gas and solid phase during emission process. In general, the formation and destruction of PCDD/Fs in the emission source were effected by the feeding characteristics of raw materials, combustion temperature, and the type of air pollution control devices (APCDs). A municipal solid waste incinerator (MSWI) and a secondary aluminum smelter (Secondary ALS) in southern Taiwan were investigated; samples of the stack flue gas, fly ash, filter cake ash, and ambient air were collected. An attempt was made to demonstrate the variation of PCDD/F onto the fly ash sources. By using a laboratory-scale packed bed reactor, the formation of PCDD/Fs was simulated under the passing of flue gas with precursor and catalyst through a bag filter. And then a Fugacity model was applied to calculate the transformation fate for PCDD/Fs.
The PAC injection rate increased from 10 to 17 kg/h in flue gas of MSWI, the concentration of PCDD/Fs I-TEQ decreased from 0.129 to 0.0290 ng I-TEQ/Nm3. The removal of PCDD/Fs can approach 99 %. The concentrations of filter cake ashes in different chambers and locations were 105–148 ng/g, which was higher than the concentration of total PCDD/Fs in fly ash (7.58 ng/g). Based on mass balance evaluation, the most significant contribution to the total PCDD/Fs released was filter cake ash (83.9 %), this value was roughly six times higher more than that of fly ash in the disposal pit, indicating that filter cake ash treatment warrants considerable attention due to the policy for controlling PCDD/Fs. These analytical results have important implications for PCDD/Fs in filter cake ash, indicating that the filter cake ash and filter treatment should be investigated extensively to control PCDD/F formation in fly ash.
In a laboratory-scale packed bed system, the packed bed was heated at 160 °C, the PCDD/Fs content of the flue gas and residue were from 605 to 1634 ng. The presence of water vapor increased the yield of PCDD/Fs, especially in the flue gas phase. Mercury (II) chloride works as a maxium role of the catalyst to promote PCDD/Fs formation, this value was roughly four times and especially in the residue phase. Results of this study provide further insight into the PCDD/F formation under realistic combustion conditions, including very low concentrations of precursors, temperature, and the presence of water in the flue gas.
The PCDD/F concentrations in stack flue gas are 103 and 3.5 fold higher than that found in workplace and ambient air. Through Fugacity Level Ⅲ, the spatial concentration distribution of PCDD/Fs released from secondary ALS in the air of the environmental media was demonstrated. The value of PCDD/Fs concentration of Fugacity model and workplace air were about 4 and 5.8 fold, and the contration of PCDD/Fs I-TEQ were about 3.4 fold. The result shows that the levels and congener profiles of PCDD/Fs of the exhaust were determined by using the Fugacity model. The obtained result could be applied to characterize the emission source of PCDD/Fs.

並列關鍵字

PCDD/Fs ； MSWI ； Secondary ALS ； Bag filter ； PAC injection ； Filter cake ash ； Fugacity

參考文獻

王琳麒，2003，污染源及大氣中戴奧辛/呋喃之特徵，博士論文，國立成功大學，環境工程學系，台南。

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