碩士生: 張家瑋
畢業年分: 2023年7月
論文名稱: 回流區特性對斜向噴流燃燒器粉煤燃燒效率的影響分析(中文) / Analysis of the effect of recirculation zone characteristics on the combustion efficiency of pulverized coal in inclined jet burner (英文)
中文摘要:
本研究提出一種結合雙斜向甲烷/空氣預混噴流與粉煤噴流進料器的撞擊式燃燒器，期望實現潔淨高效燃燒。實驗中採用粒子圖像測速（PIV）、氣體分析儀、熱電偶溫度計及掃描式電子顯微鏡（SEM），探討不同預混當量比、氣體流速、偏轉角與粉煤/空氣流速對火焰結構與燃燒特性的影響。
流場分析顯示，兩股噴流相互撞擊後形成碰撞區與回流區，前者增強動量傳遞並促進燃料與空氣混合，後者則使粉煤停留並發生熱解。熱解過程導致粉煤大顆粒因內部溫度梯度及熱壓力破碎成小顆粒，高溫下則強化裂解反應，提高甲烷與一氧化碳等揮發分產率，並於下游對衝火焰中燃燒。此機制有助於提升煤炭的清潔與穩定燃燒。
進一步分析不同操作參數，結果顯示提高甲烷/空氣流速與燃燒器中心流速可有效增進粉煤燃盡率；SEM 觀測亦確認粉煤粒徑隨操作條件變化而縮減，驗證其燃燒特性。本研究證實所提出之斜向噴流撞擊燃燒器能有效促進氣固混合與煤粉燃燒，對潔淨煤燃燒技術的發展具有應用價值。
英文摘要:
This study proposes a novel oblique jet impinging burner composed of two methane/air premixed jets and a pulverized coal jet, aiming to achieve clean and efficient combustion. Experimental techniques, including particle image velocimetry (PIV), gas analysis, thermocouple temperature measurement, and scanning electron microscopy (SEM), were employed to investigate the effects of equivalence ratio, gas velocity, deflection angle, and coal/air feed rate on flame structure and combustion characteristics.
The results indicate that the interaction of the two opposing jets forms two distinct flow structures: a collision zone and a recirculation zone. The collision zone enhances momentum transfer and mixing, while the recirculation zone retains coal particles long enough to undergo pyrolysis. This pyrolysis process promotes particle fragmentation under thermal stress and generates volatiles such as methane and carbon monoxide, which subsequently combust downstream in the counterflow flame region. SEM observations confirmed particle size reduction associated with pyrolysis, while high-temperature conditions favored more intense decomposition and improved burnout. Furthermore, increasing methane/air velocity and central flow velocity of the burner significantly enhanced coal burnout efficiency.
In conclusion, the proposed oblique jet impinging burner effectively promotes gas–solid mixing, improves coal burnout, and supports stable and clean combustion. These findings demonstrate its potential value for the development of advanced clean coal combustion technologies.
