| 摘要: | SCR早期應用在NOx之去除，後來才應用在戴奧辛之去除，利用觸媒技術對戴奧辛破壞分解已成為現今控制戴奧辛排放之主要技術。本研究分成實廠與模廠測試部份進行探討，實廠部份針對國內現有ＳＣＲ場址，對戴奧辛之排放控制採樣與調查，模廠測試部份將採用觸媒(Cu/C、Fe/C、Cu-Fe/C)進行測試，探討觸媒於不同操作條件對戴奧辛催化分解能力。 實廠部分初步結果顯示金屬冶煉廠SCR對氣相戴奧辛的去除率66%，對PCDD與PCDF之去除率分別約為67.3%與 65.4%。在垃圾焚化廠方面，該廠SCR對氣相戴奧辛的去除率約為96.9%，對PCDD與PCDF之去除率分別為96.0%與 95.8%。垃圾焚化廠蜂巢狀V2O5/WO3/TiO2觸媒表面積(870 m2/m3)遠大於金屬冶煉廠平板狀V2O5/WO3/TiO2觸媒表面積(320 m2/m3) ，所以造成煙道氣流中戴奧辛與觸媒接觸頻率較高而予以催化分解，導致垃圾焚化廠對氣相戴奧辛有較佳之去除效率。 模廠部份在金屬冶煉廠煙道氣測試結果顯示，在不同溫度下(150℃、200℃、250℃)就觸媒對戴奧辛去除效率而言，三種觸媒(Cu/C、Fe/C與Cu-Fe/C)對戴奧辛的去除效率約達95 ﹪以上。就觸媒對戴奧辛破壞效率而言，在150℃時三種觸媒對戴奧辛之破壞效率約為20~30﹪，然而隨溫度的升高，Fe/C與Cu-Fe/C觸媒對戴奧辛之破壞效率越好，當在250℃時，Fe/C觸媒對戴奧辛之破壞效率高達78 ﹪。在垃圾焚化廠煙道氣測試方面，在不同溫度下(150℃、200℃、250℃)就觸媒對戴奧辛去除效率而言，二種觸媒(Cu/C與Fe/C)對戴奧辛的去除效率約達90 ﹪以上。就觸媒對戴奧辛破壞效率而言，在150℃時觸媒之破壞效率約為30~40 ﹪，然而隨溫度的升高，Fe/C觸媒在200℃時對戴奧辛之破壞效率達66 ﹪，當在250℃時對戴奧辛之破壞效率降為57 ﹪。 在金屬冶煉廠煙道氣測試時使用Cu/C觸媒於200℃與250℃時與Cu-Fe/C觸媒於250℃時，觸媒上皆有戴奧辛生成現象產生，在進流組成不同之垃圾焚化廠煙道氣測試，Cu/C觸媒於250℃時，觸媒上有戴奧辛生成現象產生，顯示觸媒上含有Cu催化金屬和Fe催化金屬相較之下，含有Cu催化金屬利於戴奧辛之再生成發生，然而在200℃時於金屬冶煉廠煙道氣測試，Cu-Fe/C觸媒中也含有Cu催化金屬，但並未見明顯生成，可能和Cu催化金屬含量多寡及操作溫度有關。 SCR was mainly applied to removal of NOx as initially developed and now it has been used to abate dioxin emissions as well. Presently, abatement of dioxin using catalysis has become the mainstream technology. This study can be divided into two parts including field tests and pilot-scale system tests. The former focuses on sampling and investigating the control of dioxin emissions for existing SCR devices. The latter utilized several kinds of activated carbon-supported catalysts (Cu/C, Fe/C and Cu-Fe/C) to evaluate the feasibility of removing dioxins. Regarding the tests conducted in field, the results showed that removal efficiency of gas-phase dioxin achieved with SCR at metal smelting factory was 66% while that of PCDD and PCDF were 67.6% and 65.4%, respectively. For the MSWI, the SCR could remove 95% of gas-phase dioxin, in which 96% of PCDD and 97% of PCDF were removed. The surface area of the honeycomb-type V2O5/WO3/TiO2 catalyst (870m2/m3) adopted by MSWI is much higher than that of plate-type V2O5/WO3/TiO2 catalyst (320 m2/m3) utilized by metal smelting factory, resulting in the higher removal efficiency obtained in MSWI. The source of pilot-scale system sampling in metal smelting factory conducted the removal efficiencies achieved by utilizing Cu/C, Fe/C and Cu-Fe/C catalysts were as high as 95%. As for source of pilot-scale system sampling in the MSWI, the removal efficiencies achieved with Cu/C and Fe/C catalysts were more than 90%. In the metal smelting factory, the destruction efficiencies of three catalysts at 150℃ were about 20-30%. However, the destruction efficiencies obtained with Fe/C and Cu-Fe/C catalysts increased with increasing temperature. At 250℃, the destruction efficiency achieved with Fe/C catalyst was 78%. In the MSWI, the destruction efficiencies obtained with activated carbon-supported catalysts (Cu/C and Fe/C) were 30-40% when the temperature was kept at 150℃. For the Fe/C catalyst, the obtained destruction efficiency at 200℃ was 66%; however, once the temperature is increased to 250℃, the destruction efficiency was reduced to 57%. For the results of metal smelting factory, dioxin were generated through catalysis when the temperature of the Cu/C catalyst was 200℃ or 250℃ and that of the Cu-Fe/C catalyst was 250℃. In the MSWI, dioxin were generated through catalysis while the temperature of the Cu/C catalyst was 250℃. Compared with the results obtained with Cu/C and Fe/C catalysts in the metal smelting factory, it can be concluded that dioxin would be more easily produced when Cu/C catalyst is applied. Although the Cu-Fe/C contained Cu as well, no dioxin was generated at 200℃, which might be relevant to the Cu content and operating temperature. |
