請用此 Handle URI 來引用此文件: http://hdl.handle.net/11455/5658
標題: 半乾式除酸系統中操作條件對焚化廢氣污染物去除之影響
The Effects of the Operating Conditions of Spray Dryer System on the Removal Efficiency of Incineration Pollutants
作者: 吳欣益
Wu, Hsin-Yi
關鍵字: acid gas
酸性氣體
heavy metal
organic compound
spray dryer
spray pressure
重金屬
有機物
半乾式
霧化壓力
出版社: 環境工程學系
摘要: 廢棄物焚化處理技術具有減容、減量、安定及資源化等優點,因此適合地狹人稠的台灣推廣。然而在焚化過程中可能產生少量的毒性金屬,且被收集在乾灰、溼灰或以氣膠的型態排放至大氣中。酸性氣體如SOx、NOx也可能在焚化過程中產生,排放至大氣中導致酸雨的形成。有機物也是廢棄物焚化的污染物,且具有致癌性。因此,瞭解煙道氣中酸性氣體、微量重金屬及有機物在煙道氣中之行為及最佳控制方法是必要的。 多數學者曾利用鹼性吸收劑探討對模擬煙道氣中酸性物質之去除效率。然而在含有粉塵、重金屬及酸性物質之實際煙道氣中,對酸性物質之去除效率則較少被提及。此外,相較於靜電集塵器串聯濕式洗滌塔,經半乾式除酸系統串聯袋式集塵器處理後之煙道氣中有較少量的戴奧辛成份形成。因此,半乾式除酸系統可能有去除部份有機物質之可能性。 本研究即針對有害之酸性氣體、有機物及重金屬,如鉛、鉻、鎘、銅、鋅及鎳,探討半乾式除酸系統操作條件對飛灰粒徑分佈及對先前三種污染物去除效率之影響。實驗所評估的半乾式除酸系統操作參數包括(1)不同的吸收劑、(2)不同的添加劑、(3)不同的霧化壓力及(4)不同的吸收劑當量比。並利用XRD(雷射光繞射儀)探討重金屬生成物種之種類。 實驗結果顯示半乾式除酸系統對二氧化硫之去除效率介於42.23~88.20%,添加添加劑可提升二氧化硫去除效率約0.24~15.37%,單一添加劑時以碳酸氫鈉之效果較好,而混合添加劑時則以混合添加三種添加劑有較高的二氧化硫去除效率。而對重金屬之去除效率,鉛為1.21~78.53%、鉻為1.87~83.33%、鎘為23.79~92.79%、銅為14.28~95.53%、鋅為57.78~96.56%、鎳為27.69~91.58%,添加二氧化矽及碳酸氫鈉會降低除了鋅之外的其它金屬之去除效率,而添加高錳酸鉀則會增加除了鉻之外的其它金屬之去除效率。在有機物去除方面,未添加添加劑時,有機物之去除效率介於44.15~86.14%之間;添加碳酸氫鈉會降低有機物之去除效率,添加高錳酸鉀則可提升約9%之去除效率,而以混合添加二氧化矽及高錳酸鉀有較高的有機物去除效率。
Owing to the advantages of stabilization, resource recovery and reduction, incineration technique is more suitable for the congested areas, such as Taiwan. However, trace toxic metals may escape from the incineration process and subsequently be collected in dry ashes, in wet scrubbed ashes, or as airborne aerosols emitted into the atmosphere. Acid gas, such as SOx, NOx, may also escape from the incineration process, and result in the formation of acid rain. Organic compounds also are the pollutant of waste incineration, which could give rise to cancer. Therefore, it is imperative to understand the behavior of acid gas, trace heavy metals and of organic compounds in flue gas and the best method to control them. The removal efficiency of acid compounds with alkaline sorbents in simulated flue gas has been investigated in previous studies. However, the removal efficiency of acid gas in incineration flue gas, which contains dust, heavy metals, and acid gas itself, is seldomly mentioned. Furthermore, if bag house was employed after spray dryer system only less dioxin compounds were formed in the exit flue gas, compared to the electrostatic precipitator (ESP) was employed prior to the scrubber system. Therefore, it is suspected that the spray dryer system has the potential of removing part of organic compounds. Be aimed at the harmful acid gas, Organic compounds and heavy metals, such as Pb, Zn, Cd, Cr, Cu and Ni, the effects of the operating conditions of Spray Dryer on the formed particle's size and on the removal efficiency of the foregoing three pollutants were studied in present work. The operating parameters of the Spray Dryer System evaluated included (1) different absorbents, (2) different additives, (3) different spray pressure and (4) different Stoichiometric Ratio of absorbent. X-ray diffraction analysis was also carried out to determine the species of the metal species. The results showed that the removal efficiency of SO2 in Spray Dryer System were within the compass of 42.23~88.20%, and the promotion of additives on the removal efficiency of SO2 were beyond 0.24~15.37%. For single additive, NaHCO3 had bestest promotion of the removal efficiency of SO2; for complex additive, the highest enhancement of the removal efficiency of SO2 observed when the absorbent mingle with SiO2, NaHCO3 and KMnO4. SiO2 and NaHCO3 migled in absorbent could enhance the removal efficiency of heavy metals besides Zn. However, the removal efficiency of the heavy metals, with the exception of Cr, decreased due to an affix of KMnO4. The removal efficiency of the everysingle heavy metal were with the purview of: Pb: 1.21~ 78.53%, Cr: 1.87~ 83.33%, Cd: 23.79~ 92.79%, Cu: 14.28~ 95.53%, Zn: 57.78~ 96.56%, Ni: 27.69~ 91.58%. The removal efficiency of organic compounds were within the range of 44.15~86.14% with no additives. When NaHCO3 was present, the removal efficiency was decreased and increased around 9% with the presence of KMnO4, the highest removal efficiency was observed when SiO2 together with KMnO4 were present.
URI: http://hdl.handle.net/11455/5658
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