利用離散元素法計算高爐內固體流

Investigating into Solid Flow In Blast Furnace by Discrete Element Method

陳佑宗(You-Zong Chen)

指導教授 ： 蔡建雄

國立屏東科技大學/工學院/車輛工程系所/碩士(2014年)

https://doi.org/10.6346/NPUST.2014.00088

摘要

在高爐操作中，爐氣在爐身塊狀區(lumpy zone)的分配直接受到焦炭與鐵礦(燒結礦、球結礦與礦礦等)層結構所影響。為改善爐身的透氣性(permeability)與提升高爐生產效率，操作人員希望能掌握爐料的料層結構(礦焦比)以及爐料流動之特性，以作為佈料模式以及相關操作條件設定的參考。由於缺乏量測技術，尚無法在操作中之高爐進行相關之分析。為能深入探討爐料在爐料流動的特性，本研究中利用離散元素法 (discrete element method, DEM)，建立高爐爐料流動之計算模式，並利用實驗所得料層形狀分佈，與料面和爐壁間夾角來驗證相關之計算參數，驗證結果顯示實驗與模擬結果相似，證明DEM的計算準確性。在高爐模擬結果中顯示，料層的分佈情況由各位置的下降速度決定，而料層下降速度由爐頂至爐底，依序為爐中心的料層下降速度大於爐壁，到過了爐腰後，料層下降速度轉變為爐壁下降速度快於爐中心的速度。研究中也顯示爐壁的摩擦力大小是影響靠近壁面料層的下降速度的主因，而改變風徑區位置會影響到爐腰以下的料層速度，且高爐爐身角越小，爐中心的料層下降速度快於爐壁周圍的料層下降速度的趨勢就越明顯。研究中也發現往往實驗模型中容易被忽略的對稱面摩擦力，會使料層下降速度趨勢相反，使結果改變為爐壁的料層下降速度快於爐中心。另外，從結果中得知混合層的產生不只是因為落料時的撞擊，且會因大小粒子在高爐內的相對運動，造成混合層，尤其以爐壁附近混合層最為明顯。

關鍵字

高爐 ； 離散元素法 ； 料層分佈 ； 料層下降速度 ； 混合層

並列摘要

The gas distribution in the lumpy zone of blast furnace is mainly determined by the burden layer structure. For the improvement the permeability, as well as the productivity, the O/C distribution of burden layer and burden descending behaviors are always desirable for the stabilization of blast furnace operation. Owing to difficulties in the measurement, a simulation model by discrete element method (DEM) was established in this study to analyze the burden layer structure distribution and the burden descending velocity with different operation conditions, such as the location of raceway, blast furnace profile and O/C. The calculated burden layer structures and wall fraction angle were validated by the two-dimensional physical experiments carried out in this study. The calculated burden descending velocity in the center area is higher than that in the wall area. The velocity difference between the center and wall area is increased with the decrease of the bosh angle of the furnace. On the contrary, the burden velocity in the wall area becomes faster when the burden reaches the furnace belly, resulting from the burden consumption in the raceway. The calculated results indicate the formation of mixing layer is a consequence of the descending velocity difference between the coke and ferrous. With higher wall friction, the extent of the mixing layer becomes more significant.

並列關鍵字

Blast furnace ； Discrete element method ； Burden layer distribution ； O/C ； Mixing layer

參考文獻

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