本研究以一座運轉中的汙泥焚化爐為對象，針對煙道氣進行戴奧辛採樣分析。本汙泥焚化爐設備容量為12 ton/day，配備有文式冷卻塔及袋濾室集塵器，初步評估在燃燒控制及既有空氣污染防制設備對戴奧辛之去除效率。研究結果顯示，冷卻塔中段煙道氣中戴奧辛濃度為0.046 ng-I-TEQ/Nm3，其濃度遠低於煙囪排放口之濃度0.321 ng-I-TEQ/Nm3。在APCD前後採樣結果中，PCDF濃度於總戴奧辛排放濃度及總毒性當量濃度中皆佔主導地位。採樣為同步採樣，煙道氣流250℃至400℃時為戴奧辛生成之高峰區，當煙道氣流由440℃冷卻至袋濾室集塵器入口之173℃時，剛好經過戴奧辛之生成溫度窗，進而造成煙道氣中煙囪戴奧辛濃度高過冷卻塔中段，戴奧辛低溫再生成所造成的影響應為其最主要的原因。煙囪排放口之戴奧辛濃度已低於目前法規排放標準(0.5 ng-I-TEQ/Nm3)，分布於煙囪氣流中之戴奧辛物種氣固相分布幾乎各佔一半（非毒性當量濃度），表示改善後其空氣污染防制設備對固相戴奧辛之去除效果已有提升。本研究針對本土污泥焚化爐於典型操作條件下戴奧辛之排放濃度做初步探討，已充分掌握戴奧辛物種之分佈，包括高低氯數分佈、PCDD/Fs之分佈及APCD前後物種的改變。所建立之國內污泥焚化廠排氣中戴奧辛濃度資料與空氣污染防制設備對戴奧辛之去除效率資料可提供未來國內業者興建污泥焚化廠選用空氣污染防制技術及相關單位於建立戴奧辛排放資料庫或進行風險評估時之重要參考。 Evaluation of the dioxin removal efficiencies of the air pollution control devices (APCDs) at existing industrial sludge incinerator (ISI) in Taiwan is conducted via stack sampling and analysis in this study. The ISI investigated (capacity: 12 tons/day) is equipped with venturi scrubber followed by bag filter (BF). The PCDD/F concentrations measured at venturi scrubber inlet is 0.046 ng-I-TEQ/Nm3 which is lower than that measured at stack (0.321 ng-I-TEQ/Nm3). The results indicate that PCDF concentration is much higher than PCDD measured in flue gas of BF inlet and outlet in the ISI investigated. The flue gas is quenched by venturi scrubber, with the temperature being decreased from 440°C to 173°C. Therefore, the PCDD/F concentration measured at stack gas is significant higher than that measured at BF inlet because the operating temperature of the APCD falls into the temperature window of de novo synthesis (200~350°C). Besides, the results of vapor/solid-phase PCDD/F sampling also indicate that the about 50% PCDD/F congeners exist in solid phase. Hence, the removal efficiency of particle and solid-phase PCDD/F achieved with BF in the ISI investigated should be improved to further reduce its PCDD/Fs emissions. Overall, this study preliminary evaluates the PCDD/F concentration and congener distribution in flue gas of an existing ISI. The results of this study provide important references for the industry in terms of design and operation of ISIs.
