【作者】 荆德吉；

【导师】 刘剑； 葛少成；

【作者基本信息】 辽宁工程技术大学 ， 安全技术及工程， 2013， 博士

【摘要】 随着社会迅速发展,人们对粉尘污染的重视程度越来越高,粉尘治理的理论成为当今学者们研究的热点,其中粉尘颗粒逸散规律和不同控尘方法的降尘机理成为研究中的重点和难点。为模拟不同粉尘逸散规律和控尘机理,通过气固两相流理论结合粉尘颗粒特性,构建了粉尘浓度扩散二流体三维数值计算模型以及颗粒轨道三维数值计算模型。并结合实践经验修正了计算模型方程,对不同曳力模型进行深入考察检验,选取了适用于粉尘颗粒运动的曳力模型,并考虑了颗粒和壁面间碰撞作用。通过数值模拟和理论分析,结合在选煤厂皮带受料处的应用,分别研究了密封负压控尘机理和微雾控尘机理。对各粒级粉尘颗粒分别受气流变化和雾滴捕捉后的运移轨迹进行了数值模拟,得出了粉尘颗粒运动轨迹,并通过数值模拟和现场应用验证了两种控尘方法的高效性。针对粉尘颗粒在皮带受料处的运移规律,创新性地提出了闭环回旋控尘方法,基于气固两相流理论和颗粒碰撞理论,对闭环回旋控尘机理进行了三维数值模拟及理论研究。研究表明,在普遍存在的管式落料系统中,由于落料的重力加速强制诱导,管下方气流能量大于上方气流能量,通过设置闭环实现了气流的回旋流动,回旋作用有效地耗散了气流的能量,进而达到降尘目的。现场应用验证了闭环回旋气流在大落差落料系统粉尘治理中的高效性,同时,该方法无需任何动力,是未来节能型除尘产品的发展方向。结合在破碎站和落煤塔的应用,分别研究了“外阻内抑”(外围设抑尘网内部尘源点喷雾抑尘)和“内吸外抑”(塔内负压抽尘塔外喷雾抑尘)两种控尘机理。采用数值模拟、理论分析和现场实测相结合的手段,研究了风流影响下破碎站和落煤塔发尘机理、抑尘网对风流强度的抑制机理以及塔内高压气流的消除机理。通过数值模拟和现场应用,论证了“外阻内抑”和“内吸外抑”控尘方法对多粒级粉尘的控尘效果。研究结果说明,经过对不同控尘方法的理论研究,应用其控尘机理,能够有效治理不同区域粉尘污染,并且结合两种或者两种以上的综合控尘,对大型污染源有良好的治理效果。本文应用气固两相流理论对控尘理论开展深入研究,旨在为丰富控尘理论和有效降低粉尘污染等发挥有效作用。更多还原

【Abstract】 With the rapid development of society, dust pollution has been attracting much attention from people. Today, dust control theory is becoming a research hotspot, in which dust particles movement law and dust control mechanism have already become an emphasis and difficulty.Firstly, through gas-solid two-phase flow theory combining with the properties of dust particles, two-fluid model is constructed with3D that can simulate dust concentration diffusion. Besides that, particle-trajectory model is constructed with3D by DEM method that can simulate movement trajectory of dust particles.And then, dust control mechanisms of negative pressure and micro fog are studied by numerical simulation, theoretical analysis and application in coal preparation plant. Movement trajectories of various graded dust particles after airflow change and droplets capturing are simulated respectively. Dust control efficiencies about the two methods are verified by numerical simulations and field measurement.Based on movement law of dust particles in material-receiving point of belt, dust control closed-loop method is proposed innovatively. and it is discussed by numerical simulation of3D through gas-solid two-phase flow theory and particle collision theory. The results show that movement trajectory of dust particles is controlled effectively and kinetic energy of particles is reduced obviously by the closed-loop dust control. Therefore, the method of closed-loop dust control has a broad prospect for practical application.Dust control methods of "resistance outside and suppression inside" and "absorption inside and suppression outside" are tested respectively through put two theories into practice in crushing station and coal drop tower. By theoretical analysis, numerical simulation and field measurement, effectiveness of theirs dust control methods are tested and verified.The results show that theoretical analysis,3D numerical simulation and practical application of the dust control mechanism have significantly increase dust removal efficiency.更多还原