W型结构旋流器内多相流流动特性研究.pdf

国家重点研发计划资助项目（2018YFC0604702） 山东省自然科学基金资助项目（ZR2016EEM37） 博士学位论文 W 型型结结构构旋旋流流器器内内多多相相流流流流动动特特性性研研究究 Research on the Multiphase Flow Characteristics in W-shaped Hydrocyclone 作作者者姜兰越姜兰越 导导师师刘培坤刘培坤教授教授 山东科技大学 二〇二〇年六月 万方数据 中图分类号TD454学校代码10424 UDC密级公开 山东科技大学 博士学位论文 W型型结结构构旋旋流流器器内内多多相相流流流流动动特特性性研研究究 Research on the Multiphase Flow Characteristics in W-shaped Hydrocyclone 作者 姜兰越入学时间2016 年 9 月 导师 刘培坤职称 教授 申请学位 工学博士所在学院 机械电子工程学院 学科专业 机械设计及理论研究方向 固液分离 答辩日期 2020 年 6 月提交日期 2020 年 5 月 万方数据 学位论文使用授权声明学位论文使用授权声明 本人完全了解山东科技大学有关保留、使用学位论文的规定，同意本人所撰写的学位 论文的使用授权按照学校的管理规定处理。 作为申请学位的条件之一，学校有权保留学位论文并向国家有关部门或其指定机构送 交论文的电子版和纸质版；有权将学位论文的全部或部分内容编入有关数据库发表，并可 以以电子、网络及其他数字媒体形式公开出版；允许学校档案馆和图书馆保留学位论文的 纸质版和电子版，可以使用影印、缩印或扫描等复制手段保存和汇编学位论文；为教学和 科研目的，学校档案馆和图书馆可以将公开的学位论文作为资料在档案馆、图书馆等场所 或在校园网上供校内师生阅读、浏览。 （保密的学位论文在解密后适用本授权） 作者签名导师签名 日期 2020 年 6 月 12 日日期 2020 年 6 月 12 日 万方数据 学位论文原创性声明学位论文原创性声明 本人呈交给山东科技大学的学位论文，除所列参考文献和世所公认的文献外，全部是 本人攻读学位期间在导师指导下的研究成果。除文中已经标明引用的内容外，本论文不包 含任何其他个人或集体已经发表或撰写过的研究成果。对本文的研究做出贡献的个人和集 体，均已在文中以明确方式标明。本人完全意识到本声明的法律结果由本人承担。 若有不实之处，本人愿意承担相关法律责任。 学位论文作者签名 2020年 6 月 12 日 万方数据 学位论文审查认定书学位论文审查认定书 研究生在规定的学习年限内，按照培养方案及个人培养计划，完成了课 程学习，成绩合格，修满规定学分；在我的指导下完成本学位论文，论文中的观点、数据、 表述和结构为我所认同，论文撰写格式符合学校的相关规定，同意将本论文作为申请学位 论文。 导师签名 日期2020 年 6 月 12 日 万方数据 摘摘要要 在磨矿作业中旋流器作为分级分选设备得到了广泛应用，但由于多组分颗粒在旋流场 内等沉速度造成的“底流夹细”，往往引起矿石过磨，导致精矿回收率和系统处理量降低等 问题。作者基于松散分级理论，提出一种 W 型结构旋流器，该结构是将传统柱锥组合形式 改为全柱段结构，并将底流口反向插入旋流器内部形成一种“W”型式的内腔，从而通过 对旋流器内部流场的调控，实现颗粒群的松散及传质，达到降低底流夹细的目的。本文从 W 型结构旋流器内的流场分布、特殊流动形式、颗粒运动和分布等入手，采用理论建模、 数值模拟和试验验证的方法， 研究了 W 型结构旋流器内多相流流动特性及分级机理， 研究 结果具有重要的理论意义和实践意义。 首先，针对 W 型结构旋流器内气、液、固三相共存的流场特性，选择 RSM 湍流模型 用于旋流器内部高速旋转流的模拟，采用 VOF 模型获取旋流器内空气柱的动态发展特性， 采用 DPM 模型获取颗粒运动轨迹，采用 Euler 模型获取旋流分离性能。并针对 W 型结构 旋流器底部颗粒高浓度聚集的特性，基于流体动力学理论和颗粒动力学理论，对颗粒相模 型进行了修正， 充分考虑颗粒之间的相互作用， 使之更适用于 W 型结构旋流器内的颗粒运 动研究。 其次，研究了旋流器边壁结构对其内部流场和分离性能的影响。研究证明，相比于柱 锥型结构，W 型结构旋流器内流体的轴向速度减小，颗粒停留时间延长，有利于颗粒的充 分分离；同时底流口附近形成高浓度悬浮流化层，对颗粒起到淘洗的作用，可使底流夹杂 的细颗粒逸出并再次被内旋流捕集，有效减少底流夹细。针对 W 型结构进行了研究，减小 W 型结构的宽度可以提高柱段底端悬浮流化层的密度，而增加 W 型结构的高度可提高悬 浮层的厚度，经综合对比分离粒度、分离总效率和分离精度后，得到了优选的 W 型结构参 数高度比为 0.064、宽度比为 0.333。 再次，对 W 型结构旋流器内流体流动特性进行了模拟研究，全面考察了底流口直径、 溢流口直径和插入深度、柱段高度以及入口速度对旋流器内流场发展、压降、分流比、压 力场和速度场的影响规律。结果表明随底流口直径增大，旋流器压降略有降低，而分流 比逐渐增加且趋势明显，底流口直径变化对切向速度和外旋流轴向速度影响较小，而对内 旋流轴向速度影响较大；溢流管直径变化对空气柱影响很大，随着溢流管直径增大，空气 柱逐渐稳定且直径增大，同时压降和分流比都大幅度减小，内旋流轴向速度逐渐增大，零 速点逐渐向外移动；在外旋流区域，轴向速度随着插入深度的增加而减小，而在内旋流区 域，随着插入深度的增加而增大；随着柱段高度的增加，其总压降逐渐降低，在旋流器设 计时，可通过适当增加旋流器柱段高度，来降低能量损耗，增加其处理量；入口速度提高 虽然会提高离心力场强度，但入口速度增大会造成更多的能量损耗，同时流速过快缩短了 流体在旋流器内的停留时间，不利于颗粒的完全分离。 万方数据 随后，对 W 型结构旋流器内颗粒运动特性进行了研究，结果表明W 型结构旋流器 内离心惯性力和压力梯度力是重力的几百倍，径向曳力量级可达 106，是径向运动的主要 动力，且随着颗粒粒径的增大，颗粒所受径向曳力呈指数减小。在主分离区域径向离心力 随着颗粒密度的增大而逐渐升高，而压力梯度力基本不受颗粒密度变化的影响；在旋流器 底部区域，颗粒密度变化对径向离心力并无明显影响，压力梯度力则随着颗粒密度的增大 逐渐减小；随着颗粒密度的增大，颗粒所受径向曳力逐渐增大。当给料中颗粒浓度升高时， 颗粒所受径向离心惯性力和径向曳力均大幅度降低，而对压力梯度力并无明显影响。 最后，采用实验室试验测试的手段研究了溢流管直径、插入深度、底流口直径、颗粒 浓度和入口压力对 W 型结构旋流器产物浓度、 产率、 粒度及分级效率等分离性能的影响规 律，同时基于响应面法建立了以底流细颗粒含量、分级量效率和分级质效率为性能指标的 预测模型，并进行了多参数优化，得到本研究的最优参数组合。针对某铁矿磨矿分级旋流 器反富集现象严重的问题， 依据研究结果设计了Φ660mm W 型结构旋流器并应用于工业现 场。经过工业运行验证，成功将底流中-200 目颗粒含量降低了 1.46 个百分点，量效率提高 了 8.32 个百分点，返砂负荷减少了 33.38，有效解决了球磨机过磨导致精矿产率降低的 问题。 关键词关键词W 型结构旋流器；多相流；分级机理；数值模拟；试验研究 万方数据 Abstract The hydrocyclone has been widely used as a classification and separation device in grinding-classification operations. However, the “fish-hook“ caused by constant velocity settlement of multi-component particles in a swirl field can cause ore over-grinding, which leads to further problems, such as reductions in the metal recovery and the ball mill throughput. Based on the point of view of loose classification, a new W-shaped hydrocyclone was proposed. In this hydrocyclone, the conventional column-cone combination was changed to a full-column structure, and the apex was inserted back into the hydrocyclone to a W-shaped inner cavity. It was supposed to achieve the looseness and mass transfer of high concentration particles through the regulation of flow field so as to reduce the entrainment of fine particles in the underflow. In this paper, the distribution of flow field, special flow , particle movement and distribution were studied with the help of theoretical modeling, numerical simulation, experimental verification and industrial application, aiming to clarify the multiphase flow characteristics and classification mechanism of W-shaped hydrocyclone. The research results have important theoretical and practical significance. Firstly, considering that the fluid inside the W-shaped hydrocyclone included three phases, that is, gas, liquid and solid, the RSM model was applied to the simulation of high-speed rotating flow, and the VOF model was adopted to obtain the dynamic development of the air core. The DPM model was adopted to obtain particle trajectory, meanwhile the Euler model was used to simulate the separation perance. The high concentration of particles at the bottom of the W-shaped hydrocyclone was noticed. According to the theory of fluid dynamics and particle dynamics, the particle phase properties of Euler model were modified to fully consider the interaction between particles, so as to make it more suitable for the study of particle motion in a W-shaped hydrocyclone. The accuracy of the mathematical model was further verified by PIV flow field test and separation perance test. Secondly, the influence of boundary structure on the flow field and separation perance of hydrocyclone was studied. It was proved that compared with the column-cone structure, the axial velocity of the fluid in the W-shaped hydrocyclone decreases and the residence time of particles is prolonged, which is conducive to the full separation of particles. At the same time, a high concentration suspended fluidized layer is ed near the apex, which plays a role of elutriation on the particles, allowing the fine particles mixed in the underflow to precipitate out and be trapped again by the inner swirl, thus reducing the fine particles in the underflow. The optimization of W-shaped structure was studied, the results show that reducing the width of the 万方数据 W structure can increase the density of the suspended fluidized layer at the bottom of the column, and increasing the height of the W structure can increase the thickness of the suspended layer. After comparing the separation granularity, the total separation efficiency and the separation precision, the optimal W structure parameters in this study were obtained the height ratio is 0.064 and the width ratio is 0.333. Thirdly, the gas-liquid two-phase flow field in the W-shaped hydrocyclone was simulated, and the influence of the parameters such as the diameter of apex, the diameter and the insertion depth of the vortex finder, the height of the column section and the inlet velocity on the development of the flow field, pressure drop, shunt ratio, pressure field and velocity field in the hydrocyclone was investigated. The results show that, the pressure drop of the hydrocyclone decreases slightly with the increase of the diameter of apex, while the shunt ratio increases gradually with an obvious trend. The diameter change of apex has less influence on the tangential velocity and axial velocity of the external swirl, but it has more influence on the axial velocity of the internal swirl. The diameter change of the vortex finder has a great influence on the air core. As the diameter of vortex finder increases, the air core gradually stabilizes and the diameter increases. Meanwhile, the pressure drop and the shunt ratio decrease significantly. In the outer swirl region, the axial velocity decreases with the increase of the insertion depth, while in the inner swirl region, it increases with the increase of the insertion depth. As the height of the column increases, the total pressure drop decreases gradually. For the hydrocyclone design, appropriately increasing the height of the column can reduce the energy loss and increase the processing capacity. Although increasing the inlet velocity can increase the strength of centrifugal force field, it will cause more energy loss. Meanwhile, if the velocity is too fast, it will shorten the residence time of particles, which is not conducive to the complete separation of particles. Then, the motion characteristics of particles in a W-shaped hydrocyclone were studied. The results show that the radial centrifugal inertial acceleration and pressure gradient are several hundred times higher than gravity, and the radial drag force level is up to 106, which is the main driving force of radial motion. The radial drag force decreases exponentially with the increase of particle size. In the main separation region, the radial centrifugal force gradually increases with the increase of particle density, while the pressure gradient force is unaffected. At the bottom region inside the hydrocyclone, the change of particle density has no obvious effect on the radial centrifugal force. In contrast, the pressure gradient force gradually decreases and the radial drag force on the particle increases with the increase of particle density. When the feed concentration increases, the radial centrifugal inertia force and radial drag force of the particles are greatly reduced, but the pressure gradient force is not significantly affected. 万方数据 Finally, the influence of the diameter and insertion depth of vortex finder, diameter of apex, particle concentration and inlet pressure on product concentration, yield, particle size and fractional efficiency of W-shaped hydrocyclone was studied by laboratory test. At the same time, based on the response surface , a prediction model was established with the fine particles content in underflow, quality efficiency and quantity efficiency as perance indicators.The multi-parameter optimization was carried out to obtain the optimal parameter combination of this study. Aiming at the problem of serious anti-enrichment of the hydrocyclone in an iron ore dressing plant, a Φ660mm W-shaped hydrocyclone was designed on the basis of the research results and then applied to industrial sites. Through the verification of industrial operation, the content of -200 mesh particles in the underflow was reduced by 1.46 percentage points, the quantity efficiency was increased by 8.32 percentage points, and the sand return load was reduced by 33.38, effectively solving the problem of low refined mineral yield brought by ball mill overgrinding. KeywordsW-shapedhydrocyclone;Multiphase;Classificationmechanism;Numerical simulation; Experimental research 万方数据 目目录录 图清单..............................................................................................................................................I 表清单............................................................................................................................................ X 变量注释表..................................................................................................................................XII 1绪论...........................................................................................................................................1 1.1研究背景及目的意义....................................................................................................1 1.2水力旋流器研究进展综述............................................................................................2 1.3本文主要研究内容......................................................................................................10 2旋流器内多相旋转流数学模型的建立.................................................................................12 2.1旋流器理论基础..........................................................................................................12 2.2固液两相旋转流数学模型..........................................................................................18 2.3本章小结......................................................................................................................30 3旋流器边壁结构优化研究.....................................................................................................32 3.175mm 经典旋流器的模型化验证...............................................................................32 3.2边壁结构对旋流器性能的影响..................................................................................36 3.3W 型结构优选研究......................................................................................................49 3.4本章小结......................................................................................................................58 4W 型结构旋流器内流体流动特性研究.................................................................................60 4.1结构参数对 W 型结构旋流器内部流场的影响........................................................ 60 4.2操作参数对 W 型结构旋流器内部流场的影响........................................................ 79 4.3本章小结......................................................................................................................85 5W 型结构旋流器内颗粒运动特性研究.................................................................................87 5.1W 型结构旋流器内颗粒受力分析..............................................................................87 5.2W 型结构旋流器内颗粒运动行为分析......................................................................98 5.3本章小结....................................................................................................................109 6W 型结构旋流器分离性能试验研究...................................................................................111 6.1试验装置.....................................................................................................................111 6.2试验方案.................................................................................................................... 114 万方数据 6.3实验结果及分析........................................................................................................ 115 6.4工业运行验证............................................................................................................133 6.5本章小结....................................................................................................................137 7结论与展望...........................................................................................................................138 7.1主要研究结论............................................................................................................138 7.2创新点........................................................................................................................140 7.3展望............................................................................................................................140 参考文献.....................................................................................................................................141 作者简历.....................................................................................................................................152 致谢.........................................................................................................................................155 学位论文数据集..............................................