臺灣博碩士論文加值系統

本實驗採用循環式流體化床，使用內徑 80mm 之壓克力圓管，製成水平長度為 380 mm 之 L-valve 和長度為 1120mm 之下降管。固體粒子採用平均粒徑 193 µm，密度 2635 kg/m3 的砂。以量測固體流量及壓力擾動訊號，探討不同上升床速、通氣位置、通氣方向和通氣深度對 L-valve 的固體流量、壓差和標準偏差所造成之影響。
實驗結果顯示，固體流量隨通氣位置的降低和上升床流速的增加而增加。在下降管中產生大型氣泡時，標準偏差會有急劇增加的現象。由整體方面來看，通氣方向向下時的固體輸出量雖略小於水平方向通氣，但比較標準偏差可知通氣方向向下時，下降管的壓力擾動相當小，即可得到較穩定的操作。在下降管中心通氣時，固體流量下降明顯且氣體易快速進入至 L-valve 水平段，使得 L-valve 水平段的標準偏差增加。在操作 L-valve 時，增加通氣量使下降管的壓差達到最大值，則下降管中產生大型氣泡而阻礙固體流動。

The experimental apparatus consist of L-valve and downcomer made by the transparent Plexiglas columns, 80 mm i.d. The solid particles used were sand with mean particle size 193 μm. The influence of the riser velocity, aeration tap location, aeration direction and aeration depth was determined by the measurement of solid flow rate and pressure fluctuations at various pressure probes.
The results show that the solid flow rate of L-valve increased with lower aeration tap location and higher riser velocity. The standard deviation increased sharp in the formation of large gas bubbles in the downcomer. The solid flow rate of aeration downflow was slightly less than that of aeration horizontal. But the standard deviation of aeration downflow was much less than that of aeration horizontal. The solid flow rate decreased and gas entry to the horizontal section of L-valve easily and rapidly by increasing aeration depth. So the standard deviation of L-valve in aerating in centerline of downcomer was higher than that in standard operation. The pressure drop of downcomer reach its maximum value in increasing aeration. The bubbles hindered the flow of solid through the downcomer and decreased the solid flow through the L-valve.

中文摘要 I
英文摘要 II
目錄 III
圖表索引 V

一、緒論 1

二、文獻回顧 4
2-1. 非機械閥之簡介 4
2-2. 粒子種類之影響 7
2-3. L-valve 之特性 8
2-4. L-valve 之操作變數 15

三、實驗裝置與步驟 25
3-1. 實驗裝置 25
3-2. 粒子性質 33
3-3. 固體流量的量測與控制 33
3-4. 實驗步驟 35
A. 標準操作 35
B. 改變進氣方式 35
3-5. 數據分析 39




四、結果與討論 40
4-1. 在標準操作下，下降管壁不同通氣位置時 40
4-1-1. 對固體流量之影響 40
4-1-2. 對標準偏差及軸向壓力分佈之影響 44
4-2. 在標準操作下，不同上升床流速時 49
4-1-2. 對固體流量之影響 49
4-2-2. 對標準偏差及軸向壓力分佈之影響 49
4-3. 固體流量和 L-valve 壓差與文獻之比較 55
4-4. 不同的進氣方式 57
4-4-1. 通氣方向 57
4-4-1-1. 通氣方向向下 57
4-4-1-2. 通氣方向向上 61
4-4-2. 通氣深度 69
4-4-2-1. 下降管中心通氣 69
4-5. 阻滯固體流量的原因 74
4-5-1. L-valve 肘部、水平段壓力值與下降管中固體穩定移動之關係 74

五、結論 80

六、符號說明 82

七、參考文獻 84

附錄 上升床流速之計算 88

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