基于CFD的旋风分离器性能参数影响研究

发布时间：2018-04-01 19:20

本文选题：旋风分离器　切入点：CFD　出处：《山东理工大学》2015年硕士论文

【摘要】：旋风分离器是一种非常有效的粉尘分离设备,因其具有结构简单、制造成本低、维护方便等优点,被广泛应用于冶金、石油、煤炭、环保、粉体等诸多领域。虽然旋风分离器的结构简单,但是其除尘过程中筒体内部的气粒两相流动非常复杂,尚未有成熟的理论能完全解释旋风分离器内部的流动状态和颗粒的分离机理。现在常用的旋风分离器对于直径大于10μm的颗粒分离效率已经很高,然而对于小于5μm的颗粒分离能力还是不如人意。故需要改进优化分离器的各项参数,提高其分离效率;实验法有投入资金大,消耗时间长等缺点,因而近年来越来越多的研究开始选择用数值计算的方法对旋风分离器进行模拟分析并优化。本文利用CFD技术,使用ANSYS ICEM—CFD、Fluent等软件对旋风分离器内部的气相流场,气粒两相流场进行了数值计算,模拟了气体的流动以及颗粒的分离过程,具体内容为:一、通过对旋风分离器的结构特点进行分析,建立了旋风分离器的三维模型,并对其划分网格,设置边界条件;通过对不同模拟方法所得结果的对比,得出了最适合于旋风分离器的数值模拟方法:湍流模型选用雷诺应力模型、离散格式选用二阶离散格式、近壁面处理方法选用非平衡的壁面函数法。二、对旋风分离器内的气相流场进行了数值模拟,得到了分离器内部的具体流动状态:旋风分离器内部速度分布为双层旋转流结构,外部为下行涡流,内部为上行涡流,且在双层涡交界处的速度值最大;分离器内部的压力场特点是中心处压力低,两边压力高,这是排气管下口出现短路流的最主要原因;旋风分离器内部的湍流结构显示,其内部的湍流脉动十分强烈,表现出强烈的各向异性,因此雷诺应力模型较涡粘性模式适用于模拟此流动。三、对旋风分离器内的气粒两相流进行了数值模拟,观察了不同粒径的颗粒及颗粒组的运动轨迹特点:大粒径比小粒径的颗粒更容易被分离出来,且入口处颗粒入射位置的不同对颗粒的运动轨迹也有很大的影响。四、模拟分析了不同旋风分离器进口气速、排气管直径、排气管插入深度、圆柱段长度等各项参数对旋风分离器性能的影响:①旋风分离器的压力损失随着入口气流速度及排气管插入深度的增大而增大,随排气口直径及圆柱段长度的增大而减小。②旋风分离器对颗粒的分离效率随着进口速度及排气管插入深度的增大而增大,随着排气口直径及圆柱段的长度的增加增大呈现先增加后减的趋势。本文通过以上的研究,为进一步分析旋风分离器内部流动状态,提高其各项性能奠定了一定的基础。
[Abstract]:Cyclone separator is a very effective dust separation equipment, because of its simple structure, low manufacturing cost, convenient maintenance and other advantages, it is widely used in metallurgy, petroleum, coal, environmental protection, etc. Although the structure of the cyclone separator is simple, the gas-particle two-phase flow inside the cylinder is very complicated during the dust removal process. There is no mature theory to fully explain the flow state and the separation mechanism of particles in the cyclone separator. However, the separation ability of particles less than 5 渭 m is still unsatisfactory. Therefore, it is necessary to improve the parameters of the separator and improve its separation efficiency. Therefore, in recent years, more and more researches have begun to use numerical calculation method to simulate and optimize the cyclone separator. In this paper, the gas flow field inside the cyclone separator is analyzed by using ANSYS ICEM-CFDF fluent and CFD technology. The gas-particle two-phase flow field is numerically calculated, and the gas flow and particle separation process are simulated. The main contents are as follows: first, by analyzing the structural characteristics of the cyclone separator, the three-dimensional model of the cyclone separator is established. By comparing the results of different simulation methods, the most suitable numerical simulation method for cyclone separator is obtained: the Reynolds stress model is used in the turbulent model, and the Reynolds stress model is used in the turbulent model. The second order discrete scheme is used in the discrete scheme, and the non-equilibrium wall function method is used in the near wall treatment. Secondly, the gas phase flow field in the cyclone separator is numerically simulated. The specific flow state in the separator is obtained: the velocity distribution in the cyclone separator is a double-layer rotating flow structure, the external vortex is a downward vortex, the inner is an upward vortex, and the velocity value is the largest at the junction of the two-layer vortex; The pressure field inside the separator is characterized by low pressure at the center and high pressure on both sides, which is the main reason for the short circuit flow at the bottom of the exhaust pipe. The turbulence structure inside the cyclone separator shows that the turbulence pulsation inside the separator is very strong. The Reynolds stress model is more suitable than the vortex-viscous model to simulate the flow. Thirdly, the gas-particle two-phase flow in the cyclone separator is numerically simulated. The characteristics of motion trajectories of particles with different particle sizes and groups of particles are observed. The large particle size is easier to be separated than the small particle size particles, and the different incident positions of the particles at the entrance also have a great influence on the motion trajectory of the particles. The inlet gas velocity of different cyclone separators, the diameter of exhaust pipe and the insertion depth of exhaust pipe are simulated and analyzed. The influence of Cylindrical length and other parameters on the performance of Cyclone Separator the pressure loss of the 1 / 1 cyclone separator increases with the increase of inlet flow velocity and the depth of exhaust pipe insertion. With the increase of outlet diameter and cylinder length, the particle separation efficiency of cyclone separator increases with the increase of inlet velocity and exhaust pipe insertion depth. With the increase of the diameter of the exhaust port and the length of the cylinder section, there is a tendency to increase first and then decrease. Through the above research, this paper lays a foundation for the further analysis of the flow state in the cyclone separator and the improvement of its performance.
【学位授予单位】：山东理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ051.8

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