木屑於TGA及流體化床中燃燒之動力學研究

A Kinetics Study of Sawdust Combustion in TGA and Fluidized Bed

丁偉哲(Wei-Che Ting)

指導教授 ： 錢建嵩

中原大學/工學院/化學工程學系/碩士(2006年)

https://doi.org/10.6840/CYCU.2006.00424

摘要

本研究目的於使用TGA (Thermogravimetric Analyzer)及小型氣泡式流體化床燃燒爐(lab scale bubbling fluidized combustor)探討木屑之燃燒行為。首先利用TGA於不同的操作條件下以快速升溫的方式進行木屑之燃燒反應，再藉由所得的重量百分比對時間之關係數據以積分法求得木屑於燃燒過程中之反應動力參數。其次利用小型氣泡式流體化床於不同的操作條件下進行木屑之燃燒反應，並由氣體分析儀量測及計算之方式得知O2、CO與CO2濃度變化，利用碳質量平衡方式作熱重曲線(Thermogravimetric Curve，簡稱TG curve)及導數熱重曲線(Derivative Thermogravimetric Curve，簡稱DTG curve)，藉此探討木屑粒子於小型氣泡式流體化床之燃燒行為。最後，合併TGA及小型氣泡式流體化床燃燒爐實驗之結果求得二者間之關係式。
TGA實驗結果顯示，木屑之燃燒反應為一連續式二階段反應。初始為揮發物之燃燒，其次為固定碳之燃燒。且揮發物燃燒過程中不受外界氧濃度之影響，而固定碳之燃燒則與外界氧濃度有密切關係。小型氣泡式流體化床實驗顯示，木屑於五倍最小流體化速度之空床氣速下具最高之燃燒速率。

關鍵字

動力學 ； 動力 ； 熱重分析儀. 流體化床 ； 木屑

並列摘要

Abstract
The purpose of this study is to investigate the behavior of sawdust combustion using TGA and bench-scale bubbling-fluidized combustor. The reaction of sawdust combustion was carried out by in various experimental temperatures. The activation energy and pre-exponention factor of the combustion process were obtained by the Arrhenius plot on weight percentage-time figures.
The reaction of sawdust particle combustion was carried out in the bench-scale bubbling-fluidized combustor at different conditions. The concentration variations of O2, CO and CO2 in flue gas were analyzed by a gas analyzer.
The experimental result of TGA shows that the reaction of sawdust combustion was a two-stage process. The first stage is combustion of the volatile materials, and the second is the fixed-carbon. The combustion rate of volatile material was independent of oxygen concentration around the particles. But the combustion rate of fixed-carbon was dependent on oxygen concentration around the particles. The experimental result of bench-scale bubbling-fluidized combustor shows that the sawdust particle achieved the maximum combustion rate when the gas flow rate is five times of the minimum fluidization velocity.

並列關鍵字

Fluidized Bed ； TGA ； Combustion ； Sawdust ； Kinetics ； Kinetic

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