【作者】 李珺；

【导师】 刘初升；

【作者基本信息】 中国矿业大学 ， 机械设计及理论， 2014， 博士

【摘要】 随着综采机械化的广泛应用，原煤中0~6mm细粒级煤炭含量逐渐上升。大多数缺水干旱地区对细粒煤不加处理直接进入市场造成严重的资源浪费，因而亟需研究简单、可靠、高效的细粒煤分选技术及配套设备。振动流化床干法分选技术将振动能量引入传统的流化床中，形成均匀稳定的流化床层，为实现细粒煤炭的干法分选提供了有效的方法。然而，良好的分选特性需要稳定的振动环境作为保障。至今为止仍缺少对振动流化床振动特性以及复杂振动条件下的流化特性的相关研究。因此，本文针对振动机械的基本运动特征，并结合颗粒物料流态化基本过程，对直线摇摆复合振动下的流化特性和振动流化床简化力学模型的动态特性以及稳定性展开了研究，为振动流化床的工业化和大型化提供理论参考。根据细粒煤振动流化床干法分选机的分选原理和振动装置的特点，提出了新型结构振动流化床主机，确定了振动流化床主机的基本参数，初步选择了振动流化床的工艺参数，完成了新型结构振动流化床的系统设计。对振动流化床直线摇摆复合振动下的流化特性进行了试验研究。设计了具有直线摇摆复合运动的振动流化床试验平台，并利用高速动态拍摄系统分析了颗粒物料按密度分层的基本过程以及扰动条件下的物料反混过程。以振动频率、振动强度和摇摆扰动条件为试验因素进行单因素试验。发现中低频振动条件下具有较好的分选效果而高频振动无法实现分层；在摇摆扰动条件下床层内出现大气泡的产生和大范围环流，导致已分层的物料发生反混；将竖直和摇摆运动的相位差控制在0°附近可以有效避免大范围环流的产生。采用拉格朗日方程建立了振动流化床简化模型的运动方程，并利用多尺度法得到该方程的一次近似解和一次派生系统的平均方程。分析了非共振条件和1:1:2:2内共振条件下的自由振动特性。在内共振条件下，一次派生系统系数的响应幅值和频率都随初始条件的变化而变化，竖直和摇摆运动之间存在能量交换现象。利用李雅普诺夫第一方法分析了系统的运动稳定性，发现内共振条件下存在较多的不稳定因素。在振动流化床的设计过程中应该避免内共振发生。利用高速动态拍摄系统验证了平面内带有双转子的振动系统存在0°和180°相位差自同步运动。在自同步条件下，揭示了该类振动系统的受迫振动特性。求解了非共振和主共振条件下的系统受迫响应，并利用李雅普诺夫第一方法分析了系统的运动稳定性。考虑摇摆运动的高次项，利用多尺度法得到了系统在主共振条件下的频响方程，发现大幅度摇摆会导致频响曲线峰值发生偏移，从而使稳定区域缩小甚至消失。对振动流化床中试装置进行了模态分析和动力响应试验研究。利用试验模态分析获得了振动流化床的前6阶固有频率。在模态分析的基础上，测试获得了负载和空载下的振动流化床动力响应，并获得了启动、停机和稳态运行的时域和频域信号。测试结果表明启动和停机共振区附近会出现倍频振动和混沌运动，稳态运行时沿床宽方向存在一定的摆动。消除摆动和避免共振是保证良好流化环境的基本条件。更多还原

【Abstract】 The0~6mm level fine-grained coal content of raw coal gradually increase with theextensive application of fully mechanized mining, and directly accessing to marketwithout any processing of fine coal cause serious waste of resources in most dry area,thus, the research on a simple, reliable, and efficient separation technology andequipment for fine coal is significance and urgent. The vibrating energy is introducedinto the traditional fluidized bed to develop a vibrating fluidized bed (VFB) dryseparation technology, which provides a uniform and stable fluidized bed layer and aneffective way for fine coal dry separation. However, stable vibration environment is theguarantee of good separation performance. So far, relevant research about vibrationcharacteristics of VFB and fluidization characteristics under the condition of complexvibration nearly remains blank. According to the basic movement characteristics of thevibrating machine and the basic process of granular material’s fluidization, this thesispresents a study on the fluidization characteristics under the condition of liner andswing composite vibration and dynamic characteristics of simplified VFB mechanicsmodel, providing theoretical reference for the industrialization and large-scale sizeVFB.According to the separation principle of fine coal VFB dry separation machine andcharacteristics of vibration device, a novel structure of VFB is proposed, the basicparameters of VFB are determined, the preliminary process parameters of VFB areselected and system design of the VFB is completed.Experimental study is carried out to study the fluidization characteristics of VFBunder the condition of linear and swing complex vibration. The VFB testing platformwith linear and swing complex motion is designed. The basic process of densitystratification and back mixing under the disturbance condition are analyzed by using thehigh-speed dynamic system. The single-factor experiment is conducted with testingfactor of vibration frequency, vibration intensity and swing disturbance conditions,respectively, from which the conclusions are found out that better separation efficiencybrought out under conditions of low and medium frequency vibration while nostratification brought out under the condition of high-frequency vibration, big bubblesand a wide range of circulation are formed inside the bed under the swing disturbancecondition, leading the stratified materials back mixed and keeping the phase differencebetween vertical motion and swing motion around zero degree can effectively avoid theoccurrence of a wide range of circulation. The motion equations of VFB simplified model are established using Lagrangeequation. An approximate solution of the motion equations and the average equation offirst order derived system are obtained through the multiple scales method. Freevibration characteristics of non-resonance conditions and1:1:2:2internal resonanceconditions are analyzed. Under the resonance condition, both response amplitude andfrequency of coefficient of first order derived system vary with the change of initialconditions, and there exists a phenomenon of energy exchange between the vertical andswing motion. Stability of the system is analyzed with first method of Lyapunov,finding out that many factors of instability exist under the resonance condition. Theresonance condition should be avoided when the VFB is designed.The high speed dynamic system is used to verify that the in-plane vibration systemwith double rotors can achieve synchronized movement with0°and180°phasedifference. Under the condition of self-synchronization, the forced vibrationcharacteristics of this system are revealed. The forced response of system under bothnon-resonant and main resonance conditions are solved, and stability of the system isanalyzed by the first method of Lyapunov. Considering higher order terms of swingmotion, the frequency response equations under the condition of main resonance areobtained by using multiple scales method, and significant swing causing shifted peak ofthe frequency response curve is found out, so that the stable region shrink or evendisappear.Modal analysis and dynamic response experiment are conducted on the VFB pilotplant testing device. Experimental modal analysis is used to obtain the first six ordernatural frequency of VFB. Based on modal experimental analysis, the dynamicresponses of loaded and unloaded VFB are acquired, the time domain and frequencydomain signals in the starting, stopping and steady state operating period are obtained.Testing results indicate that there may be frequency-doubled oscillation and chaoticmotion nearby the resonance region of starting and stopping period, and a certain degreeof swing motion in the steady state operation period along the bed width direction.Eliminating swing motion and avoiding resonance are the basic conditions to guaranteethe good fluidization environment.更多还原