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.     

The effect of particle humidity on separation efficiency for an axial cyclone separator

The objective of this study is to investigate the effects of particle humidity on the inlet particle size distribution, overall efficiency, grade efficiency and cut size diameter for an axial cyclone separator with inner diameter of 150?mm. The collection and grade efficiencies of the cyclone separator were measured by on-line method for inlet velocities, particle concentration and particle humidity in the ranges of 12–18?m/s, 30–500?mg/m³ and 8–30‰, respectively. By employing a set of fixed parameters for inlet velocity and particle concentration, the effect of particle humidity on separation efficiency was investigated. The experimental results show that the volume ratio of larger particle increases with the increasing of particle humidity due to particle agglomeration. When the inlet velocity and particle humidity remain constant, the collection and grade efficiencies improve greatly as the increasing of the particle concentration because of the particle aggregation. However, it was noticed that the grade efficiencies did not always increased with the increasing of particle humidity under the same conditions of inlet velocity and particle concentration. The trends of grade efficiency curves for different particle humidity change at the particle diameter of approximately 10?μm. The grade efficiency improves with the increasing of particle humidity when the particle diameter is larger than 10?μm, while a contrary tendency is observed when the particle diameter is smaller than 10?μm.     

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。     

旋转直流内循环式旋风分离器流场测定与分析(Ⅰ)

采用五孔探针测试技术及相应的计算机数据采集与处理系统，测定了旋转直流内循环式旋风分离器的三维流场分布。对所测流场分4个区域进行了分析讨论，并对内循环气量进行了衡算。结果表明该新型旋风分离器设计合理，结构有利于气流中颗粒的分离。     

Parametric analysis and optimization of gas-particle flow through axial cyclone separator: A numerical study

The separation of particles through an axial swirl tube cyclone separator is numerically investigated using Eulerian-Lagrangian approach by solving Reynolds Averaged Navier-Stokes equations with RNG K-epsilon model as turbulence closure and Discrete phase modeling (DPM) of particles. The four significant geometric parameters in an axial swirl tube cyclone separator for improving the performance are identified to be blade angle, blade length, blade-tube distance and number of blades. The impact of these parameters on the output parameters of a cyclone separator, is studied through numerical analysis with the open source CFD solver OpenFOAM. A one factor analysis is performed to understand the individual contributions of the parameters and a multiobjective optimisation is done using the Design of Experiments (DoE) approach. The blade length was found to be the most sensitive parameter whereas the blade tube distance had the least effect. Using statistical methods such as Analysis of Variance (ANOVA) and Multi Objective Genetic algorithm (MOGA), a set of Pareto optimum solutions are generated, with an effective trade off between the pressure drop and filtration efficiency. The configurations obtained after optimisation are validated with CFD simulations and found to be having a better overall performance as compared to the conventional configuration.     

高温高压旋风分离器流场模拟及性能试验

提出一种圆形径向进口、筒体段扩径的拱顶旋风分离器新结构;并与PV型分离器进行了流场和分离性能对比。结果表明:在相同处理气量下,新型分离器外旋流区切向速度显著大于PV型,中心涡核区轴向速度小于PV型;用中位粒径为9μm的滑石粉进行冷模试验,新型旋风分离器分离效率比PV型高约1%;新型旋风分离器结构强度和分离性能优良,适合高温、高压的工况下应用。     

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.     

Experimental and CFD study on effects of spiral guide vanes on cyclone performance

This paper presents an experimental and numerical study on a tangential inlet cyclone separator with a spiral guide vane which is not often researched. Numerical pressure drop results were in close agreement with the experimental data. The spiral guide vane was also found to considerably influence the velocity distribution, turbulence intensity, pressure drop and collection efficiency in the cyclone. A critical value of spiral guide vane turns appeared below or above which there was a marked increase in collection efficiency, pressure drop, and tangential velocity. Compared to a cyclone with zero spiral guide vane turn, the maximal decrease in collection efficiency in the cyclone with the critical spiral guide vane turns (one turn) was 2% approximately. The maximum-efficiency inlet velocity appeared to exist independent of spiral guide vane turns, as inlet velocity affected the radial distance traveled by the rebounded particles from the inner wall. The analysis of flow field in cyclones indicated that the flow field was improved with the spiral guide vanes employed to some extent. The results presented here may provide a workable reference for the effects of spiral guide vanes on the flow field and corresponding performance in cyclone separators.     

高效、低阻分离器入口结构改进及测试分析

为了改进旋风分离器的分级除尘效率和压力损失等性能指标,通过对SLK型高效低阻分离器的分级过程和不同入口形式的旋风分离的颗粒切向速度和沉降速度的分析计算,重点研究SLK型分离器入口形式对旋风分离器内气流速度的影响及其对分级除尘效率和压力损失的影响,通过试制SLK样机并利用粉煤灰进行测试分析,定性验证SLK型分离器高效低阻的性能特点。结果表明:该分离器能获得较高的分离效率,并且压力损失比同型号分离器减小100～400Pa。     

一种新型的旋风分离器

介绍了旋风除尘器的一种新的改进方法,即在旋风除尘器的排气管处加二次流,通过控制二次流的大小及进风方向,可以改变旋风分离器内部流场分布,从而减少上灰环和短路流的产生,提高旋风除尘器的分离效率,尤其是提高其对微细粉尘的分离能力。     

旋风分离器两相流研究综述

综述了旋风分离器内部流场、颗粒运动和数值计算模型的理论研究发展历程。     

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。     

旋转管式膜分离器内流体的剪切力分布

推导了稳流下旋转管式膜器环隙间流体的轴向和径向速度,得出切向和轴向剪切力解析式以及剪切力分布曲线。在非稳流下,采用函数拟合法,得出流体切向速度随半径变化的表达式及流体所受切向剪切力和分布曲线。运用端流理论,分别讨论了水力光滑膜器内和水力粗糙膜器内轴向湍流的速度分布,得出了轴向剪切力的表达式及分布曲线。     

5000m~3/h空分设备液氮气液分离器运行控制分析

简介仪征化纤5000 m3/h空分设备中液氮气液分离器的工作原理和作用,分析气液分离器的工作状态及其对空分设备主塔运行工况的影响,论述用压力控制气液分离器工作状态的可行性,阐述其工作状态控制方法的改造建议。     

A Simplified Model to Estimate the Size Distribution Change of Polydispersed Aerosol for Cyclone Separator

ABSTRACT

Although the air-lift pump has been superseded by submersible pumps in raising water from wells and mines, it still provides an attractive means of lifting abrasive slurries because, unlike mechanical pumps, it has no moving parts to wear. However, current design of air-lift pumps must rely on empirical equations, or, at best, incremental computer solutions. Design is complicated by the fact that relative velocities of the phases change over the whole pump length. A new design equation is developed to predict the lift of an air-lift pump, given the flowrates of air, liquid and solid in the pump, and the dimensions of the air-lift tube. The new equation is baaed on well-established multiphase flow theory, and offers significant advantages over current design techniques. In combination with an equation for the overall pump efficiency, the new equation provides a method for optimizing the design parameters for the air-lift pump.     

杨树叶风振实验研究

通过研究杨树叶及其模型在不同风速下的风振变形情况,发现基于风速和叶片长度的雷诺数是单一叶片振动变形的重要气动参数.实验主要采用摄像机记录树叶变形振动过程和粒子图像测速仪测量叶片尾流流场的方法进行.实验过程中,随着风速由小变大,真实树叶依次经过了静态变形,大幅低频振荡,叶片翻卷并重归静态,由静态变为大幅高频振动等不同状态.实验表明,随着风速的增大,人造树叶经历了与真实树叶相似的状态变化过程,但各个状态的临界雷诺数与真实树叶有所不同.     

Experimental and analytical characterization of acoustic emission signals

The identification of crack growth signals is extremely important in order to effectively use acoustic emission techniques to detect, locate, and determine the significance of an internal flaw. The results of an analytical methodology, incorporating a source model that is an actual crack propagation and arrest event, are presented in this paper to predict a time dependent acoustic emission signal. The integral equation method is used to calculate the dynamic Mode I stress caused by a crack propagating with a prescribed velocity, after which the displacements at any point are calculated. These time dependent displacements are the analytical form of the acoustic emission waveforms. An experimental procedure, which uses a laser interferometer to measure velocities normal to the specimen's surface, is used to investigate acoustic emission waveforms in a compact tension specimen. The experimental results are used to verify the analytical model.     

旋风分离器内颗粒运动阻力的特征

分析了旋风分离器内颗粒运动阻力的特性,计算了某些工况下的颗粒雷诺数,进而分析说明了在旋风分离器内固体颗粒运动的的阻力不仅有粘性力的作用,而且有体形力的作用。     

Continuous Separation of Inclusions from Aluminum Melt Flowing in a Circular Pipe using a High Frequency Magnetic Field

The continuous separation of inclusions from aluminum melt flowing in a circular pipe using a high frequency magneticfield was investigated both theoretically and experimentally The separation efficiency was calculated based on thetrajectory method and compared with experimental results. It is found that the separation efficiency is a functilnondimensional parameters t_i·d_p~2B_e~2/μ_fμ_eα~2 and α/δ.The effective way to improve the separation efficiency is to increasethe effective magnetic flux density and decrease the pipe radius. and the value of α/δ should be kept about 2 in orderto obtain the optimum separation efficiency.