【作者】 朱京勇；

【导师】 王立新；

【作者基本信息】 青岛科技大学 ， 化学工程， 2007， 硕士

【摘要】 本文从理论模型、数值模拟和实验研究三个方面分析研究了惯性淘析器内气固两相流动的特性。采用FLUENT6.2模拟了淘析器内气相流场结构及固体颗粒运动行为，得到了气相速度场、压力场分布及颗粒的运动轨迹，分析了影响分级效率的结构因素，为抑制器内气体的不规则湍动和防止成品粒料溢出提供了理论依据。以数值模拟结果为指导，设计制造了高效的BIE(Bounced Inertia Elutriator)型淘析器实验设备，搭建新型惯性淘析器实验台，进行了相关流场测试与实验研究。所作主要研究工作如下：1、对惯性淘析器内气固两相流动中的颗粒进行受力分析，探讨了各种作用力对颗粒运动的影响程度。建立模型时，对气相场采用欧拉法，建立雷诺时均方程组，为使方程组封闭，引入k-ε双方程模型；对固相运动的描述则采用基于拉格朗日法的随机轨道模型。气固相的耦合问题采用四向耦合来处理，不仅考虑颗粒和气相的相互影响，还考虑了颗粒之间及颗粒与壁面间的碰撞。2、在GAMBIT 2.2中建立了惯性淘析器的几何模型并对其划分网格，提出了一种进行纵向分区划分混合网格的新方法。在FLUENT 6.2中，用基于雷诺时均方程法的标准k-ε模型对UGS型淘析器湍流场进行了数值模拟。针对UGS型淘析器各部分的改进需求设计了五个试验方案，并一一做出了模拟分析，这些探索研究为新型淘析器的开发提供了思路。设计了BIE型淘析器并对其流场进行模拟验证，计算结果表明：连接加速段和渐扩口径的内筒，有效地消除了对流段顶部环隙的短路流和死旋涡，避免了对冲气流的相互扰动；通过调整分离段长度和直径，增大了气流对颗粒的剪切力，增加了粒料的停留时间；在淘析区，下移进气位置并加入两层格栅后，该区域气流更加匀称规整，导流格栅的整流效果明显，加强了气流对粒料的淘析作用。3、在气相流场模拟的基础上，用相间耦合的随机轨道模型对两种惯性淘析器内的颗粒运动行为进行模拟，预测了不同粒径颗粒的运动轨迹，分析了颗粒在器内的速度分布情况。通过对颗粒轨迹的分析，找到了设备结构对颗粒运动行为的影响规律，BIE型淘析器独特的内构件设计有效的提高了颗粒运动的可控性。用基于颗粒追踪法的分级效率表征了两种淘析器在三种工况下的分级性能。4、测试了BIE型淘析器内不同位置的轴向速度和静压分布，测试值与模拟值吻合较好，数值模拟结果是可信的。以工业生产中的高压聚乙烯粒料为实验物料，对UGS型和BIE型淘析器进行了分离性能的测试实验，分级效率的实验值与模拟值基本一致，这说明用颗粒追踪法模拟计算分级效率是有意义的。实验结果表明，BIE型淘析器的综合分级效率比UGS型高28％左右。更多还原

【Abstract】 The behaviors of gas stream and solid discrete phase had been studied bynumerical simulation and experimental method. The commercial CFD softwareFLUENT6.2 was used to simulate the flow field in inertia elutriators. The velocityand static pressure distributions of gas phase were obtained, which had been used toanalyze structure factors affecting classification efficiency in order to restructure andimprove the performance of the equipment. Based on the numerical simulation results,high efficiency BIE elutriator equipment was developed. The main works of this studyincludes:1. The influence of each force act on particles in inertia elutriator was analyzed.For gas stream, Reynolds-averaged model based on Euler method was used and k-εmodel was applied to form algebraic finite volume equations. For solid phase,discrete phase model based on Lagrange method was used considering couplingbetween gas and solid phase, in which interaction between particles and gas, as wellas interaction between particles and wall were considered.2. The physical model of inertia elutriator was established and meshed inGAMBIT2.2. A new method that generated the grid through reasonable cutting theflow field region was put forward. The standard k-εmodel provided by FLUENT6.2was selected to simulate flow field in UGS and BIE. To meet the rebuilt request ofeach part of UGS elutriator, five projects were designed, simulated and analyzed,which provide new thoughts to develop new type elutriator. BIE elutriator wasdesigned, based on the result of simulation and experiment study. It is found that:short circuit and bad vortex in the top of convection sect were eliminated, disturbbetween mutual flow was avoided through connecting inner canister of accelerate andexpand section; share stress and stay time of particles was increased in the newelutriator. Flow field became more symmetry as gas inlet was lowered and two layersof jalousie was added. It is found that jalousie had a distinctness effect on flow field. 3. Based on flow field simulation, moving behavior of particles in the two inertiaelutriator was simulated with discrete phase model, which predicted tracks of particlesof different sizes. Equipment structure influence on particle was found throughanalyzing particle velocity distribution. The particular inner parts in BIE elutriatormade the particle movement more controllable. Separate performance in threeoperation condition was token by classification efficiency based on particle tracingmethod. The compared result showed that classification efficiency for polyethyleneparticles in BIE is 30 percent higher than in UGS.4. Using the IFA-300 and U-mould pressure meter, the flow field and staticpressure distribution had been measured in different section of BIE elutriator. Thecomparison of the experiment data and the simulation result showed that simulation isreliable, experiment is carried out using industry product polyethylene and theseparation ability of UGS and BIE is tested. The consistent experiment and simulationresult showed that it is reasonable to calculate separation efficiency with particletracing method. Best operation condition is found after repetitious experiments, inwhich integrate separation efficiency is 28% higher than UGS’s.更多还原