使用六號重油的微富氧燃燒之實驗研究

Abstract

近年來，由於能源價格的飆漲以及對環保議題的重視，如何增加能源使用效率以及減少污染排放之節能技術就成為全球研究投入的議題，而富氧燃燒技術也是其中之一。在傳統燃燒技術中，由於燃燒空氣中含有79%的氮氣，然氮氣並不參與燃燒反應，同時會帶走大量的熱，因此傳統燃燒的能源利用率偏低，而富氧燃燒正好克服了此一缺點。本研究主要針對微富氧燃燒於工業爐上之節能與污染排放特性進行實驗分析探討，本研究之氧氣濃度介於21% ~ 30%之間，燃料為6號重油為主，燃燒機則是選用工業燃燒爐所使用之燃油燃燒機，探討霧化空氣與燃燒空氣微富氧燃燒對燃燒器之污染排放、溫度分佈以及燃料消耗之影響。由於增加氧濃度可減少不反應物氮氣的含量，亦即減少煙道排氣量，故可降低排氣熱損，達到節能的效果。實驗結果顯示，燃油過剩空氣量只需6%即足以達到完全燃燒，同時氣氧濃度改變對完全燃燒所需之過剩空氣量影響並不明顯。在維持爐溫於1200 ± 10 °C，6%過剩空氣量之條件下，重油需求量由21% O2之24.0 L/hr逐步降低至30% O2之16.0 L/hr，節能量可達33.3%%以上。在NOx排放方面，在30% O2時比21% O2增加1.51倍，但NOx總排放量則降低29.4%以上。因此截至目前為止，本研究結果顯示出，燃油工業爐於霧化空氣或燃燒空氣中進行微富氧燃燒，不僅可達到降低能源使用，同時對於工業爐燃燒作業且可提升生產效率和產品產量之效。

Oxygen combustion has high energy efficiency, because the unnecessary heating of nitrogen in air is eliminated. However, the high costs of oxygen and retrofitting limits the widespread application of oxygen combustion for existing conventional air/fuel combustion systems. This study modifies the conventional air/fuel combustion system to explore the influence of oxygen concentration on combustion system performance when the oxygen concentration is limited between 21% O2 and 30% O2. Oxygen is injected into atomized-air and combustion-air in this study. The emissions, radiant heat flux, temperature distributions and fuel consumption were measured. The experimental results indicated that the increase of the oxygen concentration leads to less fuel consumption, because of the existence of less inert gas (N2). Compared with 21% O2, fuel consumption is reduced 33.3% for 30% O2 when the furnace temperature is maintained at 1200 ± 10 °C. Moreover, the NOx concentrations were increased 1.51 times but the total NOx emissions were decreased by 29.4% when the oxygen concentration increased from 21% to 30%. Meanwhile, the radiation heat flux per energy input was increased, along with the oxygen concentration.