| 摘要: | 本研究旨在以離散元素法 (DEM) 模擬高爐爐喉區域旋轉佈料行為，探討爐內各區域料層結構、粒徑分布、爐料分布特性以及孔隙率與礦焦比之變化，並建置縮小尺寸冷模實驗模型進行驗證，期望為高爐操作優化與減碳提供技術基礎。研究首先建製等比例縮小的高爐冷模裝置，選用黃豆與綠豆顆粒模擬焦炭與燒結礦，並量測其粒徑分布、密度、安息角、摩擦係數及恢復係數等物性，以確保數值模擬參數之真實性；再透過旋轉滑槽進行佈料實驗，獲得顆粒堆積輪廓與分布資料，作為數值比對依據。在模擬部分，本研究利用 EDEM 軟體建置旋轉滑槽模型，輸入參數進行佈料模擬。結果顯示，模擬與冷模實驗的顆粒分布與堆積輪廓接近，證實模型具備可靠性與準確性。進一步於全尺寸模型中，發現顆粒形狀模型的選用對料層結構合理性的影響顯著：僅以單球與雙球模型容易導致焦炭顆粒在中心區域產生不自然的平台結構，而引入三球模型後因具備更真實的幾何與滾動摩擦阻力，能有效抑制不合理滑動，使料層呈現穩定的 V 型分布。此外，不同模擬區域規模的測試也顯示，雖然縮小範圍能降低計算時間，但虛擬牆面會干擾顆粒流動並影響分布，需權衡效率與精度。在爐喉區域進行四層旋轉佈料後，結果顯示料層呈現典型的 V 字型結構，塊礦集中於外圍，燒結礦與 HBI 則沿著徑向均勻分布，而焦炭在中心區域的分布占比較高。在孔隙率方面，中心區域因大顆粒比例高而具較大空隙，因此孔隙率較高；中間區域則因小尺寸顆粒充填於孔隙中，導致孔隙率偏低、透氣性不足。礦焦比分析則顯示，外圍區域因塊礦比例較大而礦焦比較高，而中心區域則因焦炭占比高達約 70%，再加上卸料後期的大尺寸焦炭顆粒易滾入中心，造成礦焦比較低。綜合而言，本研究透過DEM 模擬，能分析高爐旋轉佈料行為與料層特性，並提供佈料操作的參考依據與孔隙率分布資料，可提升對高爐上部運行的理解與控制，為高爐煉鐵之減碳與效率改善奠定重要基礎。;This study aims to simulate the burden distribution behavior in the blast furnace throat using the Discrete Element Method (DEM), with a focus on analyzing the burden structure, particle size distribution, material distribution characteristics, and variations in porosity and coke-to-ore ratio across different regions of the furnace. A scaled-down cold model of the blast furnace was first constructed, in which soybeans and mung beans were selected to simulate coke and sinter, respectively. The particle size distribution, bulk density, angle of repose, friction coefficient, and restitution coefficient of the particles were measured to ensure realistic input parameters for numerical simulations. Burden distribution experiments were then conducted using a rotating chute to obtain particle bed profiles and distribution data for validation.
In the simulation stage, a rotating chute model was established in the EDEM software, and the measured parameters were applied. The simulation results showed good agreement with the cold model experiments in terms of particle distribution and bed profiles, confirming the reliability and accuracy of the model. In the full-scale blast furnace model, the selection of particle shape representation was found to significantly affect the reasonableness of the burden structure: using only mono-sphere or bi-sphere models tended to produce an unnatural central coke platform, while incorporating a tri-sphere model provided a more realistic geometry and rolling resistance, effectively mitigating excessive coke sliding and forming a stable V-shaped burden profile.
Further analysis of burden distribution via rotating chute simulation revealed distinct deposition behaviors among different burden types, including coke, sinter, lump ore, and hot briquetted iron (HBI). The results indicate that the burden bed exhibits a typical V-shaped profile, with lump ore mainly accumulating at the periphery, sinter and HBI distributed more uniformly along the radius, and coke predominantly concentrated in the central region. Porosity analysis showed higher porosity in the central zone due to the dominance of larger coke particles, while the intermediate region displayed lower porosity owing to the infiltration of smaller particles, leading to reduced permeability. The coke-to-ore ratio was higher at the periphery because of the greater proportion of lump ore, while the central region exhibited a lower ratio due to coke enrichment and the tendency of larger coke particles discharged later to roll toward the center.
Overall, this study demonstrates that DEM simulation can effectively capture the rotating chute burden distribution and characterize the structural evolution of the burden layer. The results provide valuable insights and reference data for optimizing blast furnace charging operations and enhancing both efficiency and carbon reduction in ironmaking processes.
Keywords: Rotating chute, Hot Briquetted Iron (HBI), Discrete Element Method, burden distribution. |
