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  • 學位論文

實驗探討水煤漿/生質煤漿挾帶床氣化爐特性

Experimental Study of the Gasification Characteristics of Bio-Char Slurry and Coal Water Slurry in Entrained Bed Gasfier

指導教授 : 楊授印
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摘要


淨煤應用關鑑技術的重點之一,為煤炭氣化技術,該技術影響整體IGCC的效能。煤炭氣化技術依煤炭進料的方式,可分為粉煤乾式進料及水煤漿濕式進料兩種。而水煤漿濕式進料其關鍵技術的重點為霧化噴嘴燃燒器,因此本研究以發展適合於挾帶床的水煤漿霧化噴嘴為主要的目標。本研究以實驗量測方法量測霧化噴嘴的冷流場霧化特性,並進一步將霧化噴嘴置於挾帶床中量測氣化特性。霧化噴嘴冷流場量測分別以粒子影像測速技術(PIV)量測霧化流場速度分布,並以Malvern雷射粒徑分析儀進行量測分析,於霧化噴嘴下方10cm、15cm、20cm處進行粒徑量測。此外,以兩種不同型態的噴嘴類型進行測試研究分別為內混氣助式噴嘴單孔及四孔兩種,並以不同的漿體濃度(10%-30%)量測其霧化錐角、粒徑分析與質量分布。以進料量10kg/hr的水煤漿挾帶床氣化爐作為實驗測試載體,其反應腔長度為1020mm、直徑為200mm,以不同噴嘴、不同的燃料(水煤漿、生質煤漿)與O/C(mole/mole)ratio探討不同參數對氣化結果的影響,並以爐內溫度分布與主要氣體產物產量(H2、CO、CO2)等主要氣體產物探討其反應特性,並以冷流場霧化特性的量測與氣化結果進行比對驗證。 結果顯示單孔氣助式噴嘴在高衝擊氣體運作時,需要較高的能量輸出,當氣體流量增加至100nl/min時,相對80nl/min與60nl/min時的霧化量有約50%的縮減;在不同的液氣比條件下,多孔噴嘴的操作範圍較單孔噴嘴操作範圍寬廣,在液體濃度30%時,單孔噴嘴中的氣體流量由60nl/min提升至80nl/min時,最低操作壓力由0.4kg/cm2提升至1kg/cm2;當氣體流量又提升至100nl/min時,最低操作壓力由1kg/cm2提升至1.4kg/cm2,而多孔噴嘴則無此現象產生。在多孔噴霧錐角中,衝擊氣體流量增加下噴霧錐角有著20%的縮減;在單孔噴嘴中,霧化錐角隨著衝擊氣體流量的增加,霧化錐角約有40%的縮減。在粒徑分析的部分,單孔噴嘴的霧化液滴粒徑小於多孔噴嘴之霧化液滴,隨著衝擊氣體流量的增加,霧化粒徑逐漸減小,當達到一定的值後,霧化液滴粒徑變化是不明顯的。在水煤漿挾帶床氣化爐的實驗中,單孔內混式噴嘴較單孔外混式噴嘴具有較高的燃燒反應,但是在提高O/C的過程中,氧氣的剩餘含量越高,整個氣化爐反應區內只有燃燒反應,氣化反應尚未出現,由於噴嘴霧化特性的關係造成此現象;生質煤漿氣化所剩餘的氧氣含量較水煤漿多,原因為生質煤漿的燃料流體特性所造成,顆粒較大的生質焦碳與纖維素造成霧化效果不佳,間接導致其反應不完全。本研究在未來將改善其噴嘴,以提高水煤漿/生質煤漿氣化反應效率與碳轉化率。

關鍵字

水煤漿 生質煤漿 氣化 霧化 挾帶床

並列摘要


The purpose of this paper is to design a nozzle suitable for coal water slurry entrained bed gasifier, in which the most suitable nozzle is found through characteristics measurement of atomized cold flow field of the nozzle and gasification of entrained bed gasifier. For measurement of atomized cold flow field, the optical measurement technique and image observation are used to explore characteristics of nozzle atomization, where particle image velocimetry (PIV) is mainly used to measure the atomized flow field and make related calculations. Malvern spray laser particle size analyzer is used for atomized particle size analysis. The particle size is measured 10cm, 15cm and 20cm respectively below the spray. The nozzle is an internally-mixing air atomizing one. The atomization characteristics are judged at different nozzle assemblies (single-hole and four-hole), liquid concentrations (10%-30%), spray cone angles, particle size analysis and mass distribution. This lab established a 10kg/gr coal-water slurry entrained bed gasifier in Nanzih District, Kaohsiung City. The reaction zone of the entrained bed is 1020mm long and 200m in diameter. The effects of different parameters on gasification results are explored at different nozzle assemblies, bio-coal slurry and O/C (mole/mole); the reaction is explored based on the temperature records of gasifier and output of main gaseous products (H2, CO, CO2); the measurement of atomization characteristics of cold flow field and the result of gasification are compared for verification. The experimental result shows that the single-hole air atomizing nozzle needs higher energy output when high flow working gas is operating. When the liquid-gas ratio is different, the operating range of the multihole nozzle is wider than that of the single-hole nozzle. However, these do not happen for the multihole nozzle. As for particle size analysis, the particle size of the atomized liquid drop of the single-hole nozzle is smaller than that of the atomized liquid drop of the multihole nozzle. With the increase of the impact gas flow, the atomized particle size reduces gradually; when it reaches a certain value, the changes of the atomized particle size become unobvious. In the experiment of the coal-water slurry entrained bed gasifier, the single-hole internally-mixing nozzle has higher reaction of combustion than the single-hole externally-mixing nozzle. This research will improve the nozzle in the future so as to improve gasification reaction efficiency and carbon conversion efficiency.

參考文獻


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[1] BP Amoco, BP Statistical Review of World Energy,2010.

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