Gas-solid separation performance and structure optimization in 3D printed guide vane cyclone separator

Low separation efficiency and large pressure drop are two common problems of cyclones. In this paper, a 3D printed guide vane cyclone separator was designed to study the separation efficiency, turbulent kinetic energy, and particle movement of particle group by experiment and simulation. The results shown that the tangential velocity was the major influence of separating. The bottom of the exhaust pipe was the main region of gas–solid separation and pressure drop. The separation efficiency and pressure drop were positively correlated with the inlet velocity and the particle radius of the fluid. The distribution of turbulent kinetic energy that leaded to the pressure drop loss was concentrated on the inlet of the exhaust pipe. The swirl has external and internal two directions. The optimized cyclone has a longer and narrower blade flow path to obtain higher separation efficiency, especially at low inlet velocity.     

Influences of inlet height and velocity on main performances in the cyclone separator

Aiming at improving collection efficiency in the cyclone separator, the effects of inlet height and velocity on tangential velocity, static pressure and collection efficiency were studied. A three-dimensional model including gas-flow, and particle-dynamics fields was built by the Reynolds stress turbulence model, and the numerical simulation was achieved using the FLUENT software. The static pressure distribution, tangential velocity distribution, and particle trajectory of the cyclone were obtained, and the variation law of the collection efficiency with inlet height and velocity as well as particle diameter was analyzed. Numerical results indicate that both the static pressure and the tangential velocity in the cyclone basically present the axial symmetrical distribution, the static pressure shows a nonlinear increasing trend in the radius direction and the distribution of the tangential velocity is in the shape of a “hump.” The increase of inlet height in a certain range reduces the rotation numbers of particles in the cyclone and shortens the residence time, which results in the improvement of trapping performance. Furthermore, the appropriately increasing inlet velocity in a reasonable range can make the collection efficiency increased.     

Effect of Vortex Finder Diameter on Flow Field and Collection Efficiency of Cyclone Separators

In this study, aerocyclone separators, with five different vortex finder diameters are simulated using commercially available computational fluid dynamics code Fluent 6.3.26 to analyze flow field pattern and the collection efficiency. It is found that a decrease in vortex finder diameter results in an increase in pressure drop by 47.84% and an increase in the collection efficiency by 9.54%, whereas, the increase in vortex finder diameter leads to a reduction in pressure drop by 23.87% and a decrease in the collection efficiency by 7.70% as compared to the Stairmand high efficiency cyclone. It is also observed that a decrease in vortex finder diameter leads to about 33% increase in axial velocity and about 25% increase in tangential velocity, whereas, an increase in vortex finder diameter results in about 23% decrease in axial velocity and about 12% decrease in tangential velocity as compared to the Stairmand high efficiency cyclone.     

旋风分离器减阻杆对流场的影响

在研究发现旋风分离器减阻杆的基础上，研究了减阻杆对流场的影响，发现了减阻杆使切向速度分布趋于平缓、轴向速度上升峰值内移、径向上压力梯度减小、轴向上中心区从逆压梯度变为顺压梯度等重要规律，从而为分析旋风分离器减阻杆的减阻机理提供了依据。同时本文还首次发现旋风分离器入口附近有近２４％的短路流量，提出设法减小这部分短路流量是提高分离效率的一个研究方向。     

混流式水轮机小开度下导水机构内湍流特性和叶道涡结构研究

为准确捕捉小开度流动的瞬态湍流特性,充分了解流场结构,采用滑移网格技术以及基于Vreman亚格子模型的全局动态大涡模拟方法,不仅得到混流式水轮机全流道内速度、压力以及涡量的分布,同时捕捉到了活动导叶周围独特的流动形式和叶道涡的时空演化。计算结果表明:当高转速、小开度工况时,流道内流体的圆周速度占有绝对优势,加强了导叶后尾迹涡的相互影响,致使流道中发生更为剧烈和复杂的漩涡、脱流等各种水力不稳定现象。从蜗壳到转轮室的压力脉动均以低频为主,主要的频率能量成分基本相同,说明小开度低频异常振动与压力波的传递有关。叶道涡是致使叶片疲劳破坏的主要因素。     

Effect of the inlet angle on the performance of a cyclone separator using CFD-DEM

Hydrodynamic characteristics in a cyclone separator are simulated by means of DEM-CFD. Reynolds stress turbulence model (RSM) is used to capture gas turbulence. By changing the inlet angle, the distributions of pressure drop, tangential and axial velocity of gas phase are obtained within the cyclone. Simulated results indicate that the flow pattern consists of two regions: loss-free vortex region and forced vortex region. The negative inlet angle brings about a larger pressure drop comparing to positive inlet angle. The separation efficiency and trajectory of particles from simulation are obtained. The effects of inlet angle and particle size on separation efficiency are quantified. The separation efficiency is increased with an increase of particle size, while the separation efficiency firstly increases and then declined as inlet angle changes from negative to positive. An agreement between the numerical simulation and experimental results has been achieved in a cyclone separator.     

Design of the new guide vane for the turbo air classifier

The guide vane is a common guide part in a turbo air classifier. However, there is a lack of a theoretical design basis and an analogy method is often used to design the guide vanes. The guide vanes’ effects of improving the flow field distribution are obtained by means of comparison of the flow field of the classifiers with and without guide vanes. However, the guide vane of a 15° setting angle should be optimized due to the non-uniform airflow circumferential distribution in the annular region. To obtain a well-distributed flow field of a turbo air classifier, a design method for the guide vane is provided based on the airflow trajectory in the volute and a new guide vane of a 10° setting angle is designed under the operating condition of 12–1200. The numerical simulation results show that the standard deviation of circumferential radial and tangential velocity is decreased. Besides, the trajectories of the particles with the same size in different circumferential positions show their classification results are consistent. This guide vane design method is feasible and provides the design references for the turbo air classifiers.     

A numerical study on pressure drop and separation efficiency of a new swirl tube cleaner

In this paper, a new design of Swirl Tube Cleaner (STC) was introduced. The performance of an STC in terms of the separation efficiency and pressure drop was numerically investigated for different vane angles, vane lengths, and inlet velocities. The Reynolds stress turbulence model was used to detect the main flow structures of the highly swirling flow inside the STC. The discrete phase model that employs the Lagrangian frame of reference was utilized for particle tracking. The results are in good agreement with experimental data available in the literature. For all cases under investigation, the main flow characteristics of the STC consist of a hub vortex flow downstream of the back cone and tip vortices in the wake flow of the vanes. Around the initiation point of the vortex flow, the centrifugal accelerations are one order of magnitude higher than that of the upstream flow around vanes. The results show that the overall separation efficiency with the specified particle size distribution can reach 88% at a pressure drop lower than 250 [Pa] for the highest flow rate. Compared to traditional STCs, the new STC decreases the pressure drop by about 50% while enhancing overall separation efficiency by approximately 2%, considering the numerical accuracy.     

Performance evaluation of a new micro gas cyclone using simulation and experimental studies to capture indoor fine particles

The aim of this study was evaluating a micro gas cyclone performance with a body diameter of 10?mm to collect indoor fine particles. The design of a cyclone requires minimizing the pressure drop and maximizing the separation efficiency. Overall and grade efficiencies, pressure drops, and cut sizes have been investigated through a theoretical model, simulation, and experimental studies. The experimental part was conducted using an Electrical Low-Pressure Impactor (ELPI) device to measure particle concentration for flow rates of 10–13.3 (l/min). In order to study the pressure drop and velocity behavior for different flow rates, COMSOL software was utilized. The obtained results from experimental work have met the theoretical and simulation outcomes adequately. It has been confirmed by all the obtained results that by increasing the flow rate and subsequently inlet velocity, the particle collection efficiency and pressure drop increase while the cut size decreases.     

Performance evaluation of industrial large-scale cyclone separator with novel vortex finder

This paper presents an experimental and numerical study on an industrial large-scale tangential-inlet cyclone separator with a novel and easy-to-implement vortex finder. The vortex finder was designed with slots on the side wall to improve cyclone performance. The collection efficiency, pressure drop, and interior flow field were analyzed. The proposed device provides an effective gas flow pathway and a coupled swirl-inertia separation mechanism, which eliminates short circuit flows under the bottom inlet of the slotted vortex finder to reduce the swirling intensity and minimize the flow instability in the separator. The pressure drop was reduced up to 27.9% compared to the conventional separator and the maximal increase in collection efficiency was 5.45%. The results presented here may provide a workable reference regarding the effects of vortex finders on improving flow fields and corresponding performance in industrial large-scale cyclone separators.     

基于FLUENT的平面涡流分级机导流特性研究

为了获取平面涡流分级机导流部分最优几何与操作参数,采用计算流体动力学软件FLUENT对其进行了数值模拟,重点研究了蜗壳与导风叶对导流效果的影响。在分析模拟所得X-Y散点数据基础上,通过建立导风叶外圈的速度、压力偏差均值与一、二次风口进风量的比例、蜗壳偏心距、导风叶定位基圆直径、导风叶数量等重要参数的关系曲线,得出了一系列较优设计目标,为平面涡流分级机导流部分的改进提供了参考依据。通过试制样机SX-35并利用粉煤灰进行筛余实验,定性验证了流体动力学分析结果在工程运用中的正确性。     

基于CFD的平面涡流分级机导流特性

采用FLUENT流体力学软件对平面涡流分级机导流部分几何参数与操作参数进行数值模拟,重点研究蜗壳与导风叶对导流效果的影响。在分析模拟所得X-Y散点数据基础上,通过建立导风叶外圈的速度和压力偏差均值与一、二次风口进风量百分比,蜗壳偏心距,导风叶定位基圆直径,导风叶数量等重要参数的关系曲线,得出一系列较优设计目标,为平面涡流分级机导流部分的改进提供参考依据。通过试制样机SX-35并利用粉煤灰进行筛余实验,定性验证了CFD分析结果在工程运用中的正确性。     

Effects of Exit Tube Diameter on the Flow Field in Cyclones

A number of cyclones with different exit tube diameters have been simulated with CFD in this study. Results show that the exit tube diameter influences not only the velocity magnitude, but also the shape of the velocity profiles within cyclones. Depending on the diameter of the exit tube, the axial velocity profiles can exhibit a either maximum or a minimum on the axis. If the exit tube diameter is small, the central flow has a jet-like appearance. On the other hand, axial velocity dip in the profile can be observed near the center in a cyclone with a large gas exit tube. In addition, the well-known double vortexes, which commonly are present in a cyclone of practical design, do not exist in a cyclone with an excessively large exit tube. Quantitative comparison of velocity distribution shows that the tangential velocity increases as the exit tube diameter is reduced, giving rise to higher particle collection efficiency. Usually, the pressure drop decreases with increasing exit tube diameter. However, if the exit tube size is excessively large, the pressure drop may start to increase. Practically, cyclone with an excessively large exit tube should be avoided.     

卧式旋风筒流场性能分析与优化

采用冷模实验方法,用五孔探针对卧式旋风筒的流场分布与阻力性能进行了实验研究,对设备的性能与技术特点做出了客观评价。通过研究看出,卧式旋风筒内气流流动主要是切向流动,径向流动最小,并且切向速度有较好的分布规律,主要是以强制涡区为主,自由涡区很小;卧式旋风筒内压损较小,仅为立式旋风筒的一半。最后对所研究的设备提出了优化改进建议。     

多效旋风分离器压降的实验研究

为了有效提高新型多效旋风分离器对粒径为0.1~3μm颗粒的分离效率,获取该设备的阻力性能,采用实验方法研究该新型多效旋风分离器压降与进口气速的关系,并与Lapple型旋风分离器进行比较。结果表明:进口风速为5~30m/s时,主体直径为0.25m的多效旋风分离器总阻力系数为7.29,其中,一级和二级预分离螺旋管的阻力系数分别为1.04和1.73;主体的阻力系数为4.52。直径为0.25m的Lapple型旋风分离器的阻力系数为7.21。     

旋转直流内循环式旋风分离器流场测定与分析(Ⅱ)

在流场测定的基础上，着重分析了旋转直流内循环式旋风分离器内三维速度分布和压力分布随入口气速的变化规律，回归了分离段切向速度计算的无因次经验方程，探求了压降性能的放大效应。结果表明该新型旋风分离器的流场规整，放大效应小，阻力系数比常用的反转式旋风分离器降低约30％。     

三维旋转流场特征与压力损失关系的研究

本文以Stairmand高效旋风分离器为实验模型，利用五孔球形探针测试了典型三维旋转流动的速度和压力分布。并结合减阻杆的研究发现，测试了安装不同类型减阻杆后速度和压力分布的变化，从而在分析减阻杆减阻机理的同时，认识了三维旋转流场特征与压力损失的关系。     

出口结构对双蜗壳式旋风分离器内流场的影响

用智能七孔球探针测试仪对不同出口结构的双蜗壳式旋风分离器内不同位置的三维速度及压力进行测量,从而获得不同结构参数对流场的影响。实验结果表明,排尘锥结构具有一定的稳流作用,有利于分离器的分离;分流型芯管的开缝有分流的作用,降低了芯管内的气流旋转强度,使上下行流都有所减少,旋风管中心附近以及边壁附近的切向速度都有所减小;分流型芯管的特有的缩口结构使不同截面上的切向速度的最大值都有所增加,距离缩口越近增加越强烈。     

Exploratory Study on Cyclones of Modified Designs

This paper introduces a new design of cyclone, named triple cyclone, created by adding two more cylinders to the conventional cyclone. The performance of the triple cyclone was evaluated systematically together with the previously reported double cyclone. The tests showed that the collection efficiencies of double and triple cyclones were lower than those of the conventional cyclone with the same body diameter and identical gas inlet and outlet size. Of the three designs, the collection efficiency of the triple cyclone was the lowest. Accordingly, the highest pressure drop was observed for the conventional cyclone, and the pressure drop for the triple cyclone was the lowest. These results are probably attributed to the relatively weak vortices formed within triple and double cyclones.     

页岩灰与催化裂化催化剂细粉旋风分离性能的对比试验研究

试验测定和对比页岩灰和流化催化裂化三旋灰(FCC三旋灰)的旋风分离器性能,考察入口气速、入口浓度对分离效率和分离器压降的影响.结果表明,在相同操作条件下,同一台旋风分离器上,粒度小于75 μm的页岩灰与FCC三旋灰的分离效率和分离器压降曲线差别显著;页岩灰的分离效率与分离器压降都明显低于FCC三旋灰,且入口浓度增大,页岩灰分离器压降的下降幅度高于FCC三旋灰;页岩灰分离效率最高的入口气流速度也低于FCC三旋灰.颗粒特性对旋风分离器的分离性能有明显影响,页岩灰和三旋灰的颗粒特性与形状差别是导致其旋风分离特性不同的一个基本原因;油页岩旋风分离器的设计应当考虑油页岩颗粒特性的影响.