摘要
【目的】流态化干法分选技术是气固两相理论在选煤领域的拓展延伸。使用干法重介质流化床对原煤进行分选时,煤炭的表面水分便随着气流携带、颗粒运动等因素在床层中运移扩散,导致加重质发生颗粒团聚现象。颗粒聚团是由于流体作用以及颗粒间耗散作用形成的颗粒富集,是一种不均匀的介尺度结构。颗粒聚团可降低流化质量,导致床层失稳,床层内部密度分布不均,产品质量变差。【方法】以颗粒碰撞黏附过程为切入点,探究潮湿条件下加重质颗粒与煤表面之间的碰撞黏附特性。【结果】结果表明,随着碰撞速度的增加,颗粒法向碰撞恢复系数呈上升趋势;相同湿度条件下,碰撞速度相同时,恢复系数随着颗粒粒径的增加而呈上升趋势;潮湿条件下流化床中颗粒间碰撞的主要能量损失为颗粒表面黏弹性损失及液桥黏附能损失,随着相对湿度的增加,液桥力引起的黏附能损失逐渐增大,颗粒恢复系数显著降低。【结论】揭示了颗粒聚团碰撞黏附机理,这为实现分选流化床中颗粒聚团的调控、维持床层稳定流化、提高流化床分选效果提供理论依据。
【Purposes】The dry fluidized-bed separation technology represents a significant advancement of the gas-solid two-phase theory within the domain of coal beneficiation.During coal separation in fluidized beds,the surface moisture of coal is transported and dispersed throughout the bed with gas flow and particle movement,resulting in particle agglomeration.Particle agglomeration refers to the accumulation of particles caused by fluid actions and dissipative interactions between particles,leading to an irregular mesoscale structure.Particle agglomeration can adversely affect fluidization quality,bed stability,density distribution,and product quality.【Methods】In this study,the collision and adhesion characteristics between heavy medium particles and the coal surface under wet conditions are investigated,focusing on the particle collision and adhesion processes.【Findings】The findings indicate that an increase in collision velocity corresponds to an increase in the normal restitution coefficient of the particles.Furthermore,under same humidity conditions and collision velocities,the restitution coefficient increases with larger particle sizes.The primary energy loss during particleparticle collisions in a wet fluidized bed is attributed to surface viscoelasticity loss and liquid bridge adhesion loss.As relative humidity increases,the adhesion loss caused by liquid bridge forces progressively rises,resulting in a significant decrease in the particle restitution coefficient.【Conclusions】The mechanism of particle agglomeration collision and adhesion is revealed from this work,providing a theoretical basis for controlling the agglomeration of particles in sorting fluidized beds,maintaining stable fluidization of the bed,and improving the sorting efficiency of fluidized beds.
作者
席童
任永鑫
李妍娇
刘尘旻
董雅妮
董良
XI Tong;REN Yongxin;LI Yanjiao;LIU Chenmin;DONG Yani;DONG Liang(Key Laboratory of Coal Processing&Efficient Utilization,Ministry of Education,China University of Mining and Technology,Xuzhou 221116,China;School of Chemical Engineering&Technology,China University of Mining and Technology,Xuzhou 221116,China)
出处
《太原理工大学学报》
CAS
北大核心
2024年第6期937-947,共11页
Journal of Taiyuan University of Technology
基金
国家自然科学基金面上资助项目(52274275)。
关键词
干法重介质流化床
磁铁矿粉
颗粒聚团
颗粒碰撞
恢复系数
dry dense medium fluidized bed
magnetite powder
particle agglomeration
particle collision
coefficient of restitution
