| 摘要: | 以氨作為氫燃料載體的潔淨能源研究，在近年來逐漸成為國際燃燒領域的重要研究議題，這是因爲相較於氫，氨具有更佳的儲運優勢，故有較佳的經濟可行性。因此，本論文針對天然氣(甲烷)和鋼廠既有燃料焦爐氣(59.6%H2、29.3%CH4、6.3%CO、2.5%CO2及2.3%N2)混入0-90%體積百分比的氨氣，使用同軸式漩流擴散燃燒器，在固定操作功率P = 2.1 kW、漩流數S = 0.84 (定義為漩渦噴嘴形成的軸向通量之角動量與主預混燃料噴嘴形成的軸向動量之比值)，在當量比phi = 0.8、1.0、1.2條件下進行燃燒試驗。藉由實驗研究，了解甲烷和焦爐氣混氨以擴散火焰燃燒時，其火焰型態、燃燒器操作範圍、汙染排放物(如氮氧化物NOx、一氧化碳CO)、殘氨等燃燒特性。結果顯示，(1)甲烷和焦爐氣混入氨氣後的焰色，會從淡藍色火焰轉變為橘紅色火焰。(2)同軸式漩流擴散燃燒器的操作範圍，會隨混氨比例的增加而縮小。例如甲烷混氨之操作範圍會從phi = 0.6-2.9 (純甲烷)縮減到phi = 1.2-1.4 (混氨比80 vol.%)。(3)有關NOx濃度量測，在純甲烷或純焦爐氣條件下，NOx濃度會隨當量比增加而上升。混入氨氣燃燒會導致NOx濃度大幅增加，但NOx濃度反而會隨當量比增加而減少。在純甲烷條件下，此同軸式漩流擴散燃燒器，其燃燒後NOx濃度從25 ppm (phi = 0.8)到40 ppm (phi = 1.2)，但當混入10 vol.%氨時，[NOx]值會大幅增加，在phi = 0.8時[NOx] = 1100 ppm，在phi = 1.2時[NOx] = 627 ppm。在純焦爐氣條件下，[NOx]值從68 ppm (phi = 0.8)增加至[NOx] = 85 ppm (phi = 1.2)。混入10 vol.%氨氣後，[NOx]值也會大幅增加，在phi = 0.8時[NOx] = 840 ppm，在phi = 1.2時[NOx] = 715 ppm。 (4)有關殘氨量測，殘氨濃度會隨混氨比例增加而增加。以phi = 1.2為例，在甲烷混10 vol.%氨氣時，殘氨濃度為0 ppm，當混氨比達到70 vol.%時，則量測到180 ppm的殘氨。若在焦爐氣混氨條件下，同樣以phi = 1.2為例，混氨比50 vol.%時，殘氨濃度為0 ppm，但在混氨比90 vol.%時，殘氨會大幅提升至2500 ppm。依據研究結果可知，混氨燃燒會對燃燒器的操作範圍和汙染物排放濃度等燃燒特性有顯著影響，故仍需進行進一步研究來克服以上問題，以期能對鋼廠未來開發低碳低汙染的燃燒技術有所助益。;Research on using ammonia as a hydrogen fuel carrier for clean energy has increasingly become a critical topic in the field of combustion research in recent years. This is because ammonia offers better storage and transportation advantages as compared to hydrogen, making it more economically viable. Therefore, this thesis investigates the combustion characteristics of natural gas (methane) and steel plant coke oven gas (COG, 59.6%H2、29.3%CH4、6.3%CO、2.5%CO2 and 2.3%N2) blended with 0-90% ammonia by volume using a coaxial swirl diffusion burner. Combustion experiments are conducted under a fixed operating power P = 2.1 kW, at a swirl number S = 0.84 (defined as the ratio of the axial flux angular momentum generated by the swirl nozzle to the axial momentum generated by the main premixed fuel nozzle), and at three equivalence ratios ϕ = 0.8、1.0、1.2. Through experimental investigations, the study aims to understand the combustion characteristics of methane and COG blended with ammonia in diffusion flames, including flame morphology, burner operating range, pollutant emissions (e.g., nitrogen oxides, NOx、carbon monoxide, CO), and residual ammonia concentrations. The results reveal the following four points, (1) When ammonia is blended with methane and COG, the flame color transitions from pale blue to orange-red. (2) The operating range of the coaxial swirl diffusion burner narrows as the ammonia blending ratio increases. For methane blended with ammonia, the operating range decreases from = 0.6-2.9 (pure methane) to = 1.2-1.4 (ammonia blending ratio of 80 vol.%). (3) Regarding NOx concentration measurements, under pure methane or pure COG conditions, NOx concentrations increase with the equivalence ratio. However, combustion with ammonia addition significantly elevates NOx concentrations, while further increases in the equivalence ratio result in a decrease in NOx levels. For pure methane conditions using the coaxial swirl diffusion burner, NOx concentrations rise from 25 ppm (ϕ = 0.8) to 40 ppm (ϕ = 1.2). When 10 vol.% ammonia is blended, the NOx concentration sharply increases, reaching approximately 1100 ppm at ϕ = 0.8 and 627 ppm at ϕ = 1.2. Under pure COG conditions, NOx concentrations rise from 68 ppm (ϕ = 0.8) to approximately 85 ppm (ϕ = 1.2). When 10 vol.% ammonia is added, NOx concentrations also significantly increase, reaching approximately 840 ppm at ϕ = 0.8 and 715 ppm at ϕ = 1.2. (4) Concerning residual ammonia measurements, the residual ammonia concentration increases with the ammonia blending ratio. For instance, at ϕ = 1.2, methane blending 10 vol.% ammonia has no residual ammonia concentration (0 ppm). However, as the ammonia blending ratio reaches 70 vol.%, the residual ammonia concentration increases to 180 ppm. Under the conditions of ammonia-blended COG, also at ϕ = 1.2, the residual ammonia concentration is 0 ppm when the ammonia blending ratio is 50 vol.%. However, when the ammonia blending ratio rises to 90 vol.%, the residual ammonia dramatically increases to 2500 ppm. Based on these aforesaid results, it is evident that ammonia-blended combustion significantly impacts the operational range of the burner and the concentrations of pollutant emissions, thereby influencing the combustion characteristics. Therefore, further research is required to address these challenges, in order to help the development of low-carbon and low-pollution combustion technologies for steel plants in the future. |
