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  • 學位論文

渦旋式流體化床燃燒爐中以煙氣迴流燃燒稻殼之研究

Combustion of Rice Husk in a Vortexing Fluidized Bed Combustor with Flue Gas Recirculation

指導教授 : 錢建嵩

摘要


稻殼為大宗生質燃料,其產量高且堆積密度小,處置上為一難題,將其當成燃料以回收熱能應為可行之的方式。本研究係於一渦旋式流體化床燃燒爐中,以矽砂為床質,進行稻殼之燃燒實驗。爐體總高4.6m,燃燒室內部為0.8m × 0.4m之矩形,乾舷區內徑為0.75m,二次空氣從乾舷區下端,距氣體分佈器2.05m高處,以切線方式通入。 本研究之操作維持進料量為40kg/hr,一次風總量為3Nm3/min,二次風總量為2Nm3/min;使用煙氣迴流探討不同過量氧率、床下計量氧比及靜床高對於爐床溫度、乾舷區溫度、一氧化碳排放、氮氧化物排放、燃燒效率及燃燒份額之影響,並與僅通入一次空氣及不使用煙氣迴流之階段燃燒作比較。 實驗結果顯示,煙氣迴流操作模式為最佳的操作模式,有最低之CO及NOx排放濃度,CO排放濃度低於61ppm,NOx排放則低於86ppm,燃燒效率95%~99%左右;由燃燒效率以及汙染物排放的角度來看,過量空氣比50%及床下計量氧比100%為最佳操作條件;靜床高須高於20cm以提供床內較好的熱傳與質傳,否則易造成床內擾動混合不佳,導致燃燒效率下降。 僅通入一次風之操作模式之NOx排放濃度最高,達118ppm,階段燃燒可有效降低NOx生成至95ppm。隨著床下計量氧上升,床區燃燒份額隨之增加;過量氧率上升時,由於過量氧由二次空氣處注入,提供乾舷區較好的燃燒氣氛,乾舷區燃燒份額增加,本研究中CO及NOx之排放濃度皆低於法規標準。

關鍵字

流體化 稻殼 生質物

並列摘要


Rice husk is a large amount of biomass energy, because of its high yield and bulk density, so that it’s a problem for disposal, it can be a fuel for converting to useful energy. In this study, combustion of rice husk was investigated in a vortexing fluidized bed combustor. Use silica sand as bed material. The combustor has a 4.6m height, 0.8m × 0.4m of combustion chamber and a 0.75 inner diameter of freeboard. The second air was inducted into the freeboard tangentially at 2.05m height above the air distributor. A vortexing fluidized bed combustor, was tested for combustion characteristics of rice-husk, feed rate maintain 40kg/hr, total primary air is 3Nm3/min, secondary air is 2Nm3/min; different operating conditions (excess oxygen ratio, air ratio, stoichiometric oxygen percentage in the bed) at flue gas recirculation operating (FGR) was utilized to discuss the axial temperature distribution, CO and NOx emissions, combustion efficiency and combustion proportion, then compare to direct combustion and stage combustion which doesn’t use FGR . The experimental results showed that the optimum operating condition is FGR, which can lower CO and NOx emissions to 61ppm and 86ppm individualy, and combustion efficiency is about 95%~99%; if taking combustion efficiency and pollutant emissions into consideration, 50% excess oxygen ratio and 100% stoichiometric oxygen percentage in the bed is the optimum operating. As stoichiometric oxygen percentage increase, the combustion proportion of bed region increase ; excess oxygen ratio increase, because the excess oxygen inject into secondary air, which provide good combustion atmosphere, causing the increasement of combustion proportion in freeboard .

並列關鍵字

rice husk fluidized-bed

參考文獻


Albina, D. O., “Emissions from multiple - spouted and spout - fluid fluidized beds using rice husks as fuel.” Renewable Energy , 31: 2152-2163 (2006).
Armesto, L., A, Bahillo., K, Veijonen., A, Cabanillas and J, Otero., “Combustion behavior of rice husk in a bubbling fluidized bed,” Biomass and Bioenergy , 23, 171-179 (2002).
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Chyang, C, S., K, T, Wu and C, S, Lin., “Emission of Nitrogen Oxides in a Vortexing Fluidized Bed Combustor,” Fuel ,86, 234-243 (2007).
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被引用紀錄


楊智雲(2015)。渦旋式流體化床燃燒爐中床內燃燒份額之研究〔碩士論文,中原大學〕。華藝線上圖書館。https://doi.org/10.6840%2fcycu201500923
王源杰(2013)。渦旋式流體化床燃燒爐中以煙氣迴流燃燒花生殼之研究〔碩士論文,中原大學〕。華藝線上圖書館。https://doi.org/10.6840%2fcycu201300905

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