流體化床燃燒爐中一氧化氮之生成機制

The Mechanism of NO Emission in Fluidized Bed Combustor

倪宏玟(Hung-Wen Ni)

指導教授 ： 錢建嵩

中原大學/工學院/化學工程研究所/碩士(2017年)

https://doi.org/10.6840/cycu201700694

摘要

本研究探討燃燒過程中，於燃料氮中之焦炭中氮元素與揮發份中氮元素對於一氧化氮生成及排放之影響。實驗於0.8 m長×0.4 m寬×4.7 m高之先導型渦旋式流體化床中進行，在固定總釋熱量130,000 kcal/hr的情況下，以焦炭、甲苯分別代表固定碳及揮發份進行混燒，當中加入吡啶、吡咯及硝基苯於焦炭或甲苯中，固定一次風風量3.5 Nm3/min、二次風風量為1.5 Nm3/min，並改變床溫(750、800、850、900°C)探討不同操作條件對於一氧化氮生成及排放之影響。

實驗結果顯示，不論是將含氮物質加入焦炭或甲苯，其混燒的結果皆顯示了床區為NO生成最主要之區域，並且隨著距離分配板高度增加而減少，至於爐出口之NO濃度因二次風之注入，使得吸附於焦炭上的氮成分與空氣中的氧氣反應形成一氧化氮，造成出口NO濃度些微上升；NO排放濃度隨著床溫上升而增加(750 ~850°C)，床溫超過850°C則下降。

燃料氮轉化成NO的轉化率之研究，以硝基形式存在的話有較高的轉化率，雜環類的部分則相對較少；無論任何含氮物質之添加，將含氮物質加入甲苯與焦炭進行混燒所得到Fuel-N轉化為NO之轉化率結果皆高於將含氮物質吸附於焦炭與甲苯進行混燒的結果，代表揮發奮中氮元素為影響NO生成之主要因素。

關鍵字

流體化床燃燒爐 ； 燃料氮

並列摘要

In this study, the effect of char nitrogen and volatile nitrogen on the formation and emission of nitric oxide in fuel nitrogen were investigated. Experiments in this study are carried out in the pilot-scale vortexing fluidized bed which is 0.8 m length × 0.4 m width × 4.7 m height. In the case of fixed total heat release(130,000 kcal/hr), co-combusted with two mode:(a) coke adsorbed model compounds and toluene,(b)coke and toluene mixed with model compounds . Total primary air is 3.5 Nm3/min and secondary air is 1.5 Nm3/min and change bed temperature (750,800,850,900℃) to explore the operation conditions for the formation and release of nitric oxide.

The results of the co-combustion show that the combustion chamber is the most important region for NO formation and decreases with increasing height, because of NO reduction with coke. Addition, the nitrogen component adsorbed on the coke reacts with the oxygen in the air to form nitric oxide, resulting in a slight increase in the NO concentration of the exit. The formation and emission concentration of NO increases with the bed temperature rise (750 to 850℃), and decreases when bed temperature over 850℃.
The conversion of fuel nitrogen to NO is studied, and in the presence of nitro has highest conversion, and heterocyclic construction is relatively small. The results of the conversion of the fuel nitrogen of the mixture of the nitrogen-containing material on toluene co-combusted with coke were higher than those of the mixture of the nitrogen-containing material on the coke and co-combusted with toluene, implied volatile-N is the major factor of NO generation.

並列關鍵字

FBC ； Volatile-N ； Char-N

參考文獻

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