摘要
在干法重介流化床的实际分选过程中,由于煤炭在尺寸、形状和密度上的显著差异,导致密度相近的煤炭在分选床层中的上升和下降速度存在差异,从而在相同分选时间内产生不同的分选效果,对分选效率产生不利影响。目前,现有的气固流化床研究多以球形颗粒为研究对象,这些研究成果难以直接应用于形状多样的煤炭实际分选过程中。此外,针对煤炭升降速度的预测研究,除TERENCE SMITH等提出的简单情形下的模型外,目前尚无适用的计算模型。为了更深入地探究煤炭尺寸与形状对其升降速度及床体分选性能的影响,揭示煤炭颗粒尺寸、形状和密度对升降行为的影响规律,并进一步优化气固分选流化床设计和提高煤炭分选效率,开展了一系列不同尺寸、形状煤炭的气固流化床分选实验,获取了入选煤炭在床层中的运动行为。基于斯托克斯定律,开发了一种经验性的预测模型,用于预测煤炭升降速度。当入选煤炭的密度在床层密度±0.1 g/cm^(3)以外时,该经验模型与不同尺寸煤炭的升降速度数据吻合良好,模型误差小于15%,能够较好地完成对煤炭升降速度与垂直位置的预测。此外,通过结合煤炭颗粒受力情况的分析,揭示了入选煤炭的尺寸、形状和密度对其在气固分选流化床中分选效率的影响规律。研究发现,相较于细尺寸煤炭,大块煤炭的分选时间更小且分选效率更高,并且其实际分选密度更接近于床层密度。此外,块状煤炭在分选过程中,块状煤炭的实际分选密度在分选过程中表现出极高的稳定性,分选密度与床层密度几乎一致。这使得其分选效果更接近于理想状态,优于相同尺寸的类扁平状和棱柱状煤颗粒。研究结果不仅为煤炭的气固分选提供了新的理论依据,也为实际工业应用中提高分选效率提供了重要参考。
In the actual sorting process of dry dense medium fluidized beds,significant differences in size,shape,and density of coal lead to variations in the rising and falling speeds of coal with similar densities within the sorting bed,resulting in different sorting effects within the same sorting time,adversely affecting sorting efficiency.Currently,existing research on gas-solid fluidized beds mainly focuses on spherical particles,making it difficult to directly apply these findings to the actual sorting process of coal with diverse shapes.Furthermore,regarding the prediction of coal rising and falling speeds,apart from the model proposed by Terence Smith and others for simple scenarios,there is currently no applicable computational model.To further explore the impact of coal size and shape on its rising and falling speeds and sorting performance in the bed,and to reveal the influence patterns of coal particle size,shape,and density on rising and falling behavior,a series of gas-solid fluidized bed sorting experiments were conducted with coals of different sizes and shapes to obtain the motion behavior of selected coal in the bed.Based on Stokes'law,an empirical prediction model was developed to predict the rising and falling speeds of coal.When the density of the selected coal is outside the bed density±0.1 g/cm^(3),this empirical model aligns well with the rising and falling speed data of different sizes of coal,with a model error of less than 15%,effectively predicting the rising and falling speeds and vertical positions of coal.Additionally,by analyzing the forces acting on coal particles,the influence patterns of the size,shape,and density of selected coal on its sorting efficiency in the gas-solid sorting fluidized bed were revealed.The study found that compared to fine-sized coal,larger coal has a shorter sorting time and higher sorting efficiency,and its actual sorting density is closer to the bed density.Moreover,during the sorting process,the actual sorting density of lump coal exhibits extremely high stability,with the sorting density nearly consistent with the bed density.This makes its sorting effect closer to the ideal state,outperforming similarly sized flat and prismatic coal particles.The research results not only provide a new theoretical basis for gas-solid sorting of coal but also offer important references for improving sorting efficiency in practical industrial applications.
作者
白龙
宋万军
周恩会
BAI Long;SONG Wanjun;ZHOU Enhui(State Energy Group Guoshen Company Shangyuquan Coal Mine,Hequ 036500,China;School of Chemical Engineering&Technology,China Uniersity of Mining&Technology,Xuzhou 221116,China)
出处
《洁净煤技术》
北大核心
2025年第S1期840-846,共7页
Clean Coal Technology
关键词
干法选煤
流化床
分选精度
浮沉行为
速度预测
dry coal preparation
fluidized bed
separation accuracy
floating and sinking behavior
speed prediction
