矩形氣泡式流體化床中氣體擴散之研究

The study of Gas Dispersion in a Rectangular Bubbling Fluidized Bed

簡清浩(Ching-Hao Chien)

指導教授 ： 錢建嵩

中原大學/工學院/化學工程學系/碩士(2008年)

https://doi.org/10.6840/cycu200900218

摘要

本研究係於40 cm × 20 cm × 150 cm之冷模流體化床中進行，分佈器採用鼓風口式、水平噴嘴式及多孔性板，可調整氣體出口孔徑以達到不同之開孔比。在短軸壁邊中心距分配板14 cm處注入二氧化碳作為追蹤氣體，並於床內各點取樣，取樣的氣體濃度以Non Dispersive Infrared (NDIR)分析濃度分佈。

本研究使用回應曲面法這種實驗設計法，目的是為了簡化實驗組數而又不失實驗結果之準確性。分別以空床氣速、開孔比、床質粒徑及分佈器種類這四個操作參數，探討與目標函數之間關連性。而設定之目標函數分別為橫向擴散係數、偏態值及峰態值。

實驗結果顯示，在四因子三水準之測試中，橫向擴散係數R-squared值為0.958，偏態值及峰態值之R-squared值分別為0.819及0.782。在個別參數效應之顯著性檢定中，橫向擴散係數除了分佈器種類之影響不明顯以外，其餘參數都有明顯之影響，尤其是空床氣速。偏態值除了空床氣速及粒徑對目標函數仍有影響以外，開孔比及分佈器種類對目標函數之影響不明顯。峰態值顯著性檢定顯示，除了粒徑對目標函數仍有影響以外，其餘實驗參對皆對目標函數之影響較不明顯。

在四因子三水準之方式檢定中，以分佈器種類這個參數之主效應影響最小，因此在修正時，刪除此操作參數，改以三個操作參數(空床氣速、開孔比、粒徑) ，以三因子三水準之方式，分別檢驗橫向擴散係數、偏態值及峰態值這三個目標函數之間的因子顯著性檢定。結果仍以橫向擴散係數，顯著性效果最好，其R-Squared值為0.975。偏態值及峰態值之R-Squared值分別為0.912即0.878。

關鍵字

回應曲面法 ； 流體化床 ； 氣體擴散

並列摘要

This study was performed in a 40 cm × 20 cm × 150 cm rectangular bubbling fluidized beds. Tuyere and horizontal-nozzle and porous plate were used to be gas distributors. Carbon dioxide was injected into the bed as the tracer gas at 14 cm above the distributor. The concentration of CO2 were detected at different positions in the bed. A Non Dispersive Infrared (ETG IMA 3000B) was used to analyze the concentration of CO2.

The design of experiment were studied using response surface methodology (RSM), which enables effect examinations of parameters with a moderate number of experiments. The operating parameters used in this study are superficial gas velocity, open-area ratio, bed material diameter ,and gas distributor. The obhective parameters used in this study are the horizontal gas dispersion coefficient, the coefficient of skewness ,and the coefficient of kurtosis.

When the experimental condition was in 4-factor-3-level, the horizontal gas dispersion coefficient, Dr, was well correlated with operating parameters and the particle and gas properties: superficial gas velocity, open-area ratio, bed material diameter ,and gas distributor, with the determination coefficient R2 of 0.966. But the coefficient of skewness, β1, and the coefficient of kurtosis, β2, were not well correlated with operating parameters, with the determination coefficient R2 of 0.819 and 0.803. Besides, we also check the effect examinations of the operating parameters. The superficial gas velocity, open-area ratio, and bed material diameter have the significant influence on the horizontal gas dispersion coefficient, while gas distributor is less remarkable. The superficial gas velocity and bed material diameter have little influence on the coefficient of skewness, while the open-area ratio and gas distributor are less remarkable. The bed material diameter have little influence on the coefficient of kurtosis, while the other operating parameters are less remarkable.

When the experimental condition in 4-factor-3-level, we can find the effect of gas distributer was much less than the other operating parameters. Next, we take superficial gas velocity, open-area ratio, and bed material diameter into account to do experiment. The result of experiment show the determination coefficient R2 of horizontal gas dispersion coefficient was 0.975. The determination coefficient R2 of coefficient of skewness and coefficient of kurtosis, were 0.912 and 0.878.

並列關鍵字

RSM ； Gas Dispersion ； Fluidized bed

參考文獻

邱華逸，【流體化床中水平噴嘴分佈器對氣體徑向混合之研究】，中原大學化工所碩士論文(2002)。

林延金，【流體化床中壓力擾動及徑向氣體混合之研究】，中原大學化工所博士論文(2003)。

劉燕莉，【氣泡式流體化床中分佈器對氣體混合效應之研究】，中原大學化工所碩士論文(2006)。

Atimtay, A. and T. Cakaloz, “An Investigation on Gas Mixing in a Fluidized Bed”, Powder Technol. 20, 1-7 (1978).

Bird, R.B., Stewart, W.E., Lightfoot and E.N., Transport Phenomena. second ed., Wiley, New York. 2002.