旋風集塵器氣流流場模擬與碳化矽微粒特徵分析

Cyclone Air Flow Field Simulation and Analysis of Characteristics of Silicon Carbide Particles

黃志宏(Chih-Hung Huang)

指導教授 ： 李嘉塗

國立屏東科技大學/工學院/環境工程與科學系所/博士(2015年)

https://doi.org/10.6346/NPUST.2015.00254

摘要

CFD套裝軟體是具有強大的運算功能，它內建的動態流體力學方程式，是具有懂得自我做理性運算、合邏輯研判的工程用物件。本研究採A與B兩組做模擬實驗設計，兩組實驗組最大的差別在於，A組的進風方式，以切線方向進入集塵器；B組的進風方式，以非切線方向進入集塵器。兩組的進風口位置，皆分別設有高、中、低三個進風口（出風口還是依照傳統，設計在頂端），分別做不同的試驗比較。經過兩組不同進風口位置的嘗試，模擬結果顯示：（1）進風方式切齊於表面者，無論位置在高中低哪個位置，產生的渦旋氣流，皆順暢於進風方式非切齊於表面者。（2）進風方式沒有切齊於表面者，無論位置在高中低哪個位置，產生的渦旋氣流，皆不順於進風方式切齊於表面者。（3）在固定風速下，渦旋旋轉越順暢，落塵量越少；渦旋氣流旋轉越不順暢，落塵量越多。(4)進風口位在高處者，可以增加落到底部的落塵量至最大；位在中間處者，落塵量次之；位在低處者，落塵量最小。(5)進氣口設計在上方位置，讓集塵器柱體內部，形成廣大穩定的底部流場，最容易使塵埃受重力落下，擁有最佳集塵效能（率）。(6)旋風集塵器設計之初，是以非切線方向，進入內部流場的方式，且進氣口位置置於高處者，最能使落塵量達到最大，最能有效提升集塵器的集塵效能（率）。
旋風集塵器的實際操作中，在出風口搭配手提式微粒計算器，檢測不同尺度的粒徑大小，可採集到6種粒徑範圍的樣本。(7)6種粒徑尺度皆表示，單位時間(60秒)下，設定的轉速越小時，出氣口可以捕捉到逸散的微粒顆粒數量越多，就表示集塵效能（率）是越不好的。以電子顯微鏡SEM觀察，微粒(SiC)在10.0μm尺度下：(8)未經過旋風集塵器的運轉分離前，還帶有油性與水氣，顆粒黏滯度高，微粒輪廓不明顯，較難分出單一顆粒的粒狀外觀特徵。(9)經過旋風集塵器的運轉分離後，沒有帶有油性與水氣，粒狀輪廓明顯，單一顆粒的粒狀外觀特徵，可以輕易分別出來，可識別的微粒數量也較多。微粒(SiC)在2.5μm尺度下，情況相同。(10) 後續的計算顯示，轉圈數越高（50圈＞40圈＞30圈），風速越快，形成穩定的層流流場，微粒自然沉降，集塵效能（率）最高。旋風集塵器有了高落塵量（集塵效能）、低壓力耗損（低壓力水頭），可以做為評估此一旋風集塵器的好壞標準。

關鍵字

氣流流場 ； CFD ； 切線方向 ； 落塵量 ； 集塵效能(率) ； 微粒特徵

並列摘要

CFD packaged software is endowed with the strong operation function. It is in-built with the dynamic fluid dynamics equation, which can serve as an object for engineering in terms of conducting the rational operation and logical judgment. This study adopts A and B two groups of simulative experimental design, the biggest difference between which lies in that the air intake method for Group A is entering the dust collector in the tangent direction, while that for Group B is in the non-tangent direction. The air intake position for both groups is all separately installed with three of high, medium and low air intakes for the different test comparison respectively. (Air outlet still conforms to the traditional design by being located on the top.) Going through with the test of two groups with different air intake positions, the simulation results suggest: (1) For the group with the air intake method even cut with the surface, the resulting vortical air flow is all smoother than that with the air intake method uneven cut with the surface, no matter where the position is high, medium or low. (2) For the group with the air intake method uneven cut with the surface, the resulting vertical air flow is all not smoother than that with the air intake method even cut with the surface, no matter where the position is high, medium or low. (3) At the fixed wind speed, the smoother the vortex rotates, the little the dust fall is; the non-smoother the vertical air flow rotates, the more the dust fall is. (4) The high position of the air intake can maximally increase the dust fall at the bottom; the medium position has the fewer dust fall; the low position results in the minimum dust fall. (5) The design of the air intake on the top position can make the inside of the column of the dust collector form a vast of stable bottom air flow field. It is easiest to let the dust fall under gravity so as to boast of the best dust collection efficiency. (6) In the beginning, the cyclone dust collector is designed to enter the inner air flow field in the non-tangent direction. Besides with the position of the air intake located high, it enables to maximize the dust fall and effectively enhances the dust collection effect of the dust collector at its best.
During the actual operation of the cyclone dust collector, the accompaniment of the handheld pellet calculator in the air outlet can detect the pellet caliber at different sizes and collect the samples at six ranges of pellet caliber. (7) All six ranges of pellet caliber indicate that at the unit time (60 sec.), the smaller the rotating speed is set, the more the number of dissipated pellets caught on the air outlet is. It means the efficiency of the dust collector is poorer. With the observation by the electronic microscope SEM, (SiC) pellet is under the size of 10.0 μm: (8) Before the rotation and separation by the cyclone dust collector, the pellet is oily with water air and high viscosity. Since the contour of the pellet is not apparent, it is difficult to distinguish the features of the pellet outlook of one single pellet. (9) After the rotation and separation by the cyclone dust collector, the pellet is free from oil and water air and the pellet contour is obvious; it can easily discern the features of the pellet appearance of one single pellet and the number of pellets is more, accounting for the majority. The situation is the same for the pellet (SiC) under the size of 2.5μm. (10) Subsequent calculations show that the higher the number of turns (50 laps> 40 laps> 30 laps), the faster the wind speed. The formation of a stable laminar flow field, let particle fall naturally, the maximum dust collection efficiency. The cyclone dust collector boasts of high dust fall (high dust collecting efficiency) and low voltage consumption (low water head) and it can be referred to as a standard for the assessment of the good or bad quality of the cyclone dust collector.

並列關鍵字

Air flow field ； CFD ； Tangent direction ； Dust fall ； Dust collecting efficiency ； Pellet features

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