| 摘要: | 本研究以離散元素法模擬高爐爐頂料倉中爐料顆粒的運動行為，分析無鐘罩式(Bell-less-type)高爐進料系統中料倉進料時顆粒的分布，以及卸料時料流的質量流率和各爐料的體積佔有率。首先進行焦炭、塊礦、燒結礦、球結礦、熱壓鐵塊(HBI)…等爐料顆粒的物理參數及機械性質參數量測實驗，量測出爐料的安息角、容積密度、摩擦係數、恢復係數…等參數，接著於DEM模擬中建立爐料顆粒模型，並使用與實驗相同的方法進行安息角、容積密度的量測模擬，最後將模擬與實驗量測結果進行比對驗證，確認模擬中爐料顆粒的參數調校，再進一步進行高爐爐頂料倉進料與卸料模擬。
依據中鋼高爐爐頂料倉尺寸，於模擬中建立等比例的料倉模型。將焦炭顆粒填入料倉，研究有無積料盒(Stone box)對於焦炭粒徑分布之差異，結果顯示安裝積料盒之後，料流撞至積料盒使料流一分為二。比較其粒徑分布，發現安裝積料盒可減少料倉中粒徑偏析(Size segregation)的現象。另外，將焦炭顆粒分別填入於左、右料倉，分析兩者的進、卸料差異，由於料倉頂部輸送皮帶的進料位置不對稱於雙料倉的中心軸，導致料倉上方的爐料偏左，使左料倉進料的料流速度大於右料倉。經模擬分析後，右料倉的粒徑偏析情形比左料倉嚴重，更多的大顆粒聚集於右料倉的壁面，使卸料時較多的大顆粒在最後排出料倉。另外，本研究的三組模擬中，右料倉卸料的平均質量流率皆大於左料倉。
使用HBI和燒結礦模擬含鐵爐料料倉的裝料情形，改變HBI顆粒填入於料倉中的先後順序，因HBI顆粒的尺寸比其他爐料顆粒大，須研究其是否會影響料倉卸料時的質量流率，如果顆粒在排料口發生架橋(Arching)現象，爐料無法下至高爐內，將被迫停止高爐生產。模擬中HBI顆粒分別於一開始、中間、最後時段填入於料倉中，再進行卸料。由結果可知，若一開始將HBI顆粒填入料倉中，卸料時會發生架橋現象，故應避免在進料時間的前段即將HBI填入料倉中。在中間、最後時段將HBI顆粒填入於料倉的模擬中皆未發生堵塞之情形。但兩者相比，在中間時段填入HBI，其料倉卸料時的質量流率相對穩定，故進料時間中段填入HBI顆粒為較佳的填料次序。
;This study uses the Discrete Element Method (DEM) to simulate the particle flow behavior in the hopper of a blast furnace. The objectives are to analyze the particle distribution in the hopper during the material charging process in a bell-less charging system, as well as measure the mass flow rate and the volume fraction of different materials during discharge. To achieve these goals, firstly we measured the physical properties of materials used in the blast furnace including coke, lump ore, sinter, pellet, and hot briquetted iron (HBI), etc., through the experiments. The properties are the angle of repose, bulk density, friction coefficient, and restitution coefficient of the materials. The properties such as the angle of repose and bulk density, created in DEM were also calibrated and verified by the experimental results. After the calibration of particle properties, the materials were charged into the hopper to simulate the particle flow behavior.
The geometry for the DEM simulation is on the basis of the hopper on the top of the blast furnace at China Steel Corporation. The effect of installing and not installing a stone box inside the hopper on the particle flow behavior was investigated. The simulation results show that the size segregation of particles inside the hopper with a stone box for the buffer was mitigated. In the simulation, the coke charging into the hopper is used to study the difference between whether there is a stone box or not. The simulation results show that the size segregation in the hopper can be reduced by installing the stone box. Furthermore, the study investigates the charging and discharging differences between the left and right hopper. It is found that the charging position of the conveyor belt at the top is asymmetric to the center axis of the dual hopper. This leads to the leftward deviation of the burden flow, resulting in a higher flow velocity in the left hopper compared to the right hopper. So more large particles gather on the wall of the right hopper, and the particle size segregation of the right hopper is more severe than that of the left hopper. In the three sets of simulations in this study, the average mass flow rate of discharge from the right hopper was higher than that of the left hopper.
In the simulation of the iron-bearing material being charged into the hopper, using sinter and HBI, the sequence in which HBI particles are filled into the hopper is varied. Since HBI particles are larger in size compared to other burdens, it is important to study whether their charging sequence affects the mass flow rate during discharge. The concern is that if particle arching occurs, it could significantly impact the Ironmaking process. If HBI particles are initially charged into the hopper, arching occurs during discharge. However, no arching occurred when charging HBI particles into the hopper in the middle and final stage, and compared to the results of charging HBI particles during the final stage, the simulation with HBI particles charged during the middle stage showed a more stable mass flow rate during discharge. |
