动力煤高g值振动筛分机理及双激励源协同调控理论与方法

As one of the vibrating screens of steam coals, the high g screen whose material projection acceleration can reach up as high as 30-50g has the following advantages: the screening efficiency and processing capability per screen panel area are higher, the wet agglomerates can be separation easily, and the Screen aperture can hardly be blocked. However, the large alternating loads leads to failure of the screen panel, the screen frame and beam in a short time, and thus decreases the lifetime of the screen. This project proposes a novel driving scheme based on the investigation of the separation and break mechanism of wet agglomerates, and to predict the optimal g-value which can achieve high-efficiency screening and decrease the damage of the screen simultaneously. Firstly, the energy rule of particle separation is determined by establishing liquid bridge and discrete element models of particles of wet agglomerates, and the mechanisms of agglomeration, separation and leaking screen of particles are revealed. Secondly, the material-screen panel-guard plate-coupled dynamic model is established by discrete element method and nonlinear finite element method, and the optimal g-values for material projection under different moisture content, coal property and material feeding amount conditions are predicted. Finally, the double-exciting scheme for floating and fixed boxes is proposed based on the dynamic parameters determined by the coupled dynamic model. The optimal g-values for material projection under different conditions can be obtained by cooperative controlling, by which both the exciting force of the fixed box and the damage of the screen can be decreased simultaneously. The achievements of the research is capable of providing basic theory for the high-efficiency, safety and low-carbon of high g screens, and is of theoretical significance and economic value.

在动力煤深度筛分装备中，以物料抛射加速度达到30-50g的高g筛的筛分效率最高，易于打散潮湿团聚物，单位面积处理量大、筛孔不易堵塞。然而，在大交变载荷作用下，高g筛筛板损耗快，筛框/横梁易开裂，影响装备使用寿命。为此，本项目在潮湿物料团聚分离机理研究基础上，提出独立双驱动方案，在保证高效深度筛分的同时，有效降低筛机关键部件加速度值。建立颗粒液桥力模型和离散元模型，找到团聚物分离临界能量，揭示细粒煤团聚、分离规律；采用离散元方法和非线性有限元方法建立物料-筛板-挡板耦合动力学模型，找到不同物料条件下团聚物抛射分离所需的最优g值；依据耦合动力学模型参数，提出浮动筛框与固定筛框双激励方式，通过协同控制策略研究，实现不同条件下物料抛射所需的最优g值，达到降低高g筛激振力，延长筛机使用寿命的目标。本项目的研究可为高g值振动筛分装备的高效、安全、低碳运行提供基础理论，具有重要的理论意义和经济价值。

高g值弛张型振动筛是高效的动力煤深度筛分关键装备，但其长期承受大的交变载荷的工作特点决定其易出现结构损伤而影响生产，减小对弛张筛结构破坏的最有效措施是降低机体工作g值。本项目在潮湿细粒煤团聚分离机理和与筛板耦合作用机理研究基础上，提出采用凹凸形貌筛板、加装回弹挡板及固定筛框与浮动筛框独立双驱动等创新方案，达到兼顾高筛分效率和长使用寿命的目标，为高g值振动筛分装备的高效、安全和低碳运行提供基础理论。本项目通过建立团聚物一对多壁面离散元模型，探讨了不同含水量及固液接触角团聚物内聚颗粒间静态液桥力分布规律。考虑弛张筛筛板的材料非线性及变形非线性，通过建立筛板有限元模型，分析了弛张筛筛板挠曲形态、材料参数、结构参数及筛孔分布对筛板运动的影响规律。在上述研究基础上，开展了团聚物-筛板耦合动力学分析，研究了不同边界条件下团聚物与弛张筛柔性筛板碰撞解聚分离规律。开展了物料群-弛张筛的耦合动力学分析，分析了不同筛板驱动参数下物料群颗粒及团聚物的运动规律及筛分解聚特性。团聚物解聚程度及物料群的筛分效率受弛张筛筛板振动特性及触筛几率的影响，为了进一步提高团聚物的碰撞解聚程度及物料群筛分效率，提出采用凹凸形貌弹性筛板增大团聚物的碰撞力，加装回弹挡板提高物料的运动复杂性及触筛几率；探讨了不同形貌筛板的筛分解聚特性及挡板高度对物料群颗粒筛分过程及筛分效果的影响。筛分过程中物料群颗粒运动产生的时变激励会加剧弛张筛固定筛框与浮动筛框的相对运动波动，为了使固定筛框与浮动筛框按理想状态振动，提出了双激励源协同驱动方案；根据双激励源弛张筛的振动微分方程，研究了基于交叉耦合的转速同步和相位补偿的双激励协同控制策略；试验结果表明协同控制策略可使双激励源弛张筛两筛框同步振动并达到理想相位差。