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.     

Effects of helical fins on the performance of a cyclone separator: A numerical study

This study aimed to investigate the separation performance of a cyclone separator after reshaping its cylindrical body by installing the helical triangular fins. A numerical simulation based on Fluent was adopted to perform an orthogonal test to optimise the structure of the cyclone separator with helical triangular fins. Three structural parameters of the helical triangular fins were selected as optimisation variables: base width, fin size, and fin pitch, and their influences on the evaluation indices of the cut-off diameter were investigated. The optimal combination scheme was determined by range analysis, and the cyclone separator performances before and after optimisation were compared and analysed. The significant influence of the structural parameters on the cut-off diameter was in descending order as the fin pitch, fin size, and base width. For particles with diameter of 0.1, 0.5, 1, 2, and 3 μm, the separation efficiency of the cyclone separator with optimized helical triangular fins increased by 7.4 %, 15.9 %, 20.1 %, 10.9 % and 14.8 % respectively. Moreover, the cut-off diameter of the finned cyclone separator is reduced by 30.7 %, while the pressure drop is only increased by 6.6 %. The short circuit flow and back-mixing were alleviated, thereby considerably enhancing the stability of the flow field. Therefore, the finned cyclone separator was found to play a critical role in increasing the separation of fine particulate matter.     

Numerical study on the performance of swirl tube based on orthogonal design

Here, an axial flow cyclone separator is design is proposed. The effects of varying the structural parameters and operating conditions on pressure drops and separation efficiency were investigated via a numerical simulation approach. The results show that of the three structural parameters considered, the distance between the diffuser and blade is the most significant factor impacting separation performance compared to the blade pitch and blade shaft diameter. Increasing the distance between conical outlet and blade can decrease its pressure drops and increase separation efficiency; while increasing the shaft diameter can increase pressure drops, and the increasing blade pitch can decrease both the pressure drop and the separation efficiency. The pressure drop of the optimized swirl tube was 102.1 Pa, with a corresponding separation efficiency of 95.04% for 100 μm particles at an extraction ratio of 10%. Further, the cut-off particle size can reach 3 μm, demonstrating that the swirl tube offers good separation performance and has the potential to be widely applied in industrial gas–solid separation applications.     

Experimental study on the separation performance of a novel gas–liquid separator

A novel two-stage dynamic separator called high-gravity cyclone separator (HGCS) has been designed for gas–liquid separation. It is mainly composed of a cyclone chamber and rotary drum. In this study, its performance, including the separation efficiency and pressure drop, is experimentally investigated, and the effects of the operating conditions and drum parameters are evaluated. For droplets with a mean diameter of 7 μm, the results indicate that the optimal gas inlet velocity and high-gravity factor are 12 m/s and 59.4, respectively, and the separation efficiency reaches 98 %. The effect of liquid concentration is sensitive to the high-gravity factor. At a liquid concentration of 57 g/m³, the maximum efficiency will be 98.75 % when increasing the high-gravity factor to 85.6. Furthermore, a smaller radial height is preferable when the gas inlet velocity is greater than 12 m/s, and a better separation efficiency can be obtained by increasing the drum length to 190 mm. However, when the length is 235 mm, the efficiency will be poor because of the Kelvin–Helmholtz and Rayleigh–Taylor instabilities. Compared with the predominant roles of gas inlet velocity, drum length and radial height in pressure drop, the effects of liquid concentration and high-gravity factor are small.     

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.     

PM2.5细颗粒物分离技术的数值模拟和性能改进

旋风切割器是分离细颗粒物的主流技术,为了提高其分离效率并减少能耗,本文分析了切割器参数对粒子分离的影响.基于计算流体动力学数值模拟的方法,分析了VSCC型旋风切割器的内部湍流流场,比较15~25L/min范围内不同流速下的涡流变化情况;基于"逃逸率"概念,模拟1~6μm内不同粒径的细小粒子逃逸率随流速的变化曲线,考察临界粒径dc并结合气溶胶实验进行验证,分析流速对分离性能的影响程度;之后考察了流速对压降的影响,提出一种几何参数改进方案,在避免压降升高的前提下提高分离性能.研究表明:流速影响旋风切割器内的湍流分布,随着流速增大,临界粒径变小,分离性能得到提升,模拟结果在16 L/min的流速下,临界粒径约为2.5μm,与实验结果基本一致,并且利用曲线给出计算总分离效率的思路;调节几何参数可以实现在低能耗的前提下,将临界粒径进一步降低为1.1μm,收集效率更高.研究结果可为PM2.5切割器的商业选择或工程设计提供理论参考.     

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.     

空调用高效旋流油分离器仿真优化与实验

为了提高空调系统中旋流油分离器的分离效率、降低压力损失,本文对其结构参数进行了优化设计,通过流体仿真研究了油分离器内部各参数对分离效率和压力损失的影响,得到最佳的参数尺寸比例,并据此制作了一款新型油分离器,安装在空调系统中进行实验测试。实验结果表明:新型油分离器在回油工况(最低制冷剂流速)下分离效率由95.5%提高到99.0%,名义制冷工况下分离效率由97.3%提高到99.6%;名义制冷工况下压力损失由55.2 k Pa降低至23.1 k Pa;同时获得了油滴颗粒的分布函数。     

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.     

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。     

CFD simulation of a novel design of square cyclone with dual-inverse cone

The objective of the present study is to propose a novel design to improve the separation efficiency of the conventional square cyclone. For this purpose, the conical section of the conventional square cyclone with single-cone is modified to dual inverse-cone. In addition, the effect of second-cone length on the performance of cyclone is considered. A three-dimensional numerical simulation is done by solving the Reynolds averaged Navier-Stokes equations with the Reynolds Stress Model (RSM) turbulence model and applying the Eulerian-Lagrangian two-phase method. The turbulent dispersion of particles is predicted by the application of the Discrete Random Walk (DRW) model. The numerical results demonstrate that dual inverse-cone square cyclone although produces higher pressure drop but its separation efficiency is higher than the square cyclone with single-cone. This is due to a smaller separation zone and shorter path of particle movements which force the particles exit from the outlet section of the cyclone. Finally, using dual-inverse cone square cyclone reduces the 50% cut size about 10% and 30% for inlet velocities of 12 m/s and 28 m/s, respectively.     

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。     

Effect of the operation temperature on the hydrodynamics and performances of a cyclone separator

The effect of the operation temperature on the cyclone hydrodynamics and performances is numerically investigated by Computational Fluid Dynamics (CFD). When increasing the temperature, the separation efficiency decreases and the separation quality improves due to the weakened double layer swirling flow structure. The radial drag and centrifugal forces exerted on 0.1 μm and 1 μm particles are recorded. A large radial drag force to centrifugal force ratio is required for escape: a ratio larger than 10⁴. When the radial drag force to centrifugal force ratio is in the range of 10¹ to 10³, it is the temperature-dependent flow field which determines the submicron particle separation. While the locus of gas zero vertical velocity is closely related to the particle’s separation, the gas turbulence intensity distribution also contributes the capture of the particles.     

Evaluation of natural gas dehydration in supersonic swirling separators applying the Discrete Particle Method

The natural gas flow fields and particles separation characteristics were numerically calculated with the RNG k ? ε turbulence model and Discrete Particle Method (DPM) in the supersonic swirling separator. An experimental system was set up for testing the separation efficiency of three new designed separators with wet air. The numerical results showed that the new annular nozzle not only expanded the natural gas to supersonic velocity with resulting in low temperature (?72 °C), but also strengthened the swirling flow with the centrifugal field of 640 000g (g is the acceleration of gravity), both of which created good conditions for natural gas dehydration. Under the strong swirling flow field, most particles collided with the walls or entered into the liquid-collection space directly, while only few particles escaped together with the gas flow. The separation efficiency reached over 95%, when the length of the cyclone separation section was about 10 times of the diameter of the wall at throat. The experimental results indicated that the water can be efficiently removed from the wet air. The numerical results were in good agreements with the experimental findings, which demonstrated that the Discrete Particle Method (DPM) was accurate and stable enough to evaluate the dehydration characteristics of the supersonic swirling separator.     

Experimental investigation of processes in acoustic cyclone separator

This paper presents air flow velocity profiles obtained in conventional and acoustic cyclone separators. It is shown that vortex air flow is created in acoustical cyclone separator in presence of secondary countercurrent air flow. It is obtained that in acoustic cyclone separator air pressure pulses occur at frequency of 8 kHz and pressure amplitude reaches a value of 170 dB. Separation efficiency of acoustic cyclone separator was established experimentally.     

Transport hydrodynamics of catalytic particles in gradient cyclonic flow field and reaction characteristics to produce bio-oil

For the purpose of improving product yield and reducing energy consumption, a novel cyclonic integrated catalytic process was established for the biomass vapors upgrading based on simultaneous reaction-separation technology. In order to gain better insights into the biomass pyrolysis vapors upgrading in this heterogeneous system of novel gradient cyclonic flow field, the particle transport hydrodynamics, the product distribution characteristics and operating parameters effects in the newly developed uniflow cyclone reactor were explored by experimental and numerical simulation methods. The results demonstrate that the gradient cyclonic flow field has a positive effect on the contact efficiency and separation effect, and then beneficially promote catalytic reactions. During the movement of catalysts in the gradient cyclonic flow field, a catalyst-cluster is observed near the top of the reactor with a dense “body” and a dilute “shadow”. The characteristics of secondary vortexes and solid concentration distribution on radial and axial directions were further explained. The optimal reaction temperature, reaction time and catalyst to vapors mass ratio to produce bio-oil respectively are 550 °C, 1.5 s and 24.0. This work provides theoretical basis for optimization of reactor structure and operation parameters. It is beneficial to the improvement of biomass catalytic pyrolysis technology.     

CFD-DEM simulation and optimization of gas-cyclone performance with realistic macroscopic particulate matter

Most of research concerns have been focused on developing new methods and parameters to make the cyclone separator performance better. In this work, the inverse-flow cyclone type geometry was performed and optimized through the modulation of changing the position and dimensions of the involute inlet portion and cyclone barrel section length at a fixed inlet air velocity of 30 ms^?1. Cyclones of different inlet sizes and portions were computationally modeled which named as cyclones I, II, III, IV, and V. The study was successfully accomplished for two heterogeneous groups of particulate matter mixed with air flow for applications pertinent to agricultural engineering. To capture the phenomena of constitutive air-granular materials behavior in the optimized separator, numerical simulations were generated using one-way coupling of commercial ANSYS-Fluent® 18.0 (CFD) and Rocky® 4.13 (DEM) software, which is considered as the first head start research approach in the cyclonic separation and purification field. Discrete Element Method (DEM) which was represented by Rocky® package simulates the movement of each particle individually, taking into consideration the interaction and collision of the particles. Whereas, the highly curved streamlines and the chaotic turbulence of the continuum air flow in the cyclone separator were modeled through the Computational Fluid Dynamics (CFD-Fluent®) technique using advanced turbulence model RNG $k-\epsilon$. The numerical results successfully captured the effects of new geometrical modifications done on the original cyclone separator. Numerically, the cyclone inlet height significantly improved the cyclone performance by increasing the separation efficiency, cleaning efficiency, and cyclone effectiveness, while other parameters had a negative effect. These data were useful for considering cyclone (III) as the most suitable modification and optimization design geometry for harvesting jojoba seeds with the lowest operation cost and highest performance.     

Numerical and experimental investigations of the effects of the breakup of oil droplets on the performance of oil–gas cyclone separators in oil-injected compressor systems

A numerical simulation was conducted of the dynamic trajectories and the separation performance of oil droplets, with a focus on the breakup of oil droplets in an oil–gas cyclone separator. The separation efficiency was also studied experimentally, and the oil droplets' diameter distributions before and after the separator were measured with a Malvern particle size analyser to verify the simulation model. Both the experimental and simulation results showed that the breakup of oil droplets occurred in the separation process, clearly influencing the separation efficiency. In addition, the results indicated that inlet velocity played an important role in separation efficiency, as it not only significantly affected the tangential velocity inside the separator, but also determined the possibility and degree of the breakup of oil droplets.     

循环流化床锅炉用旋风分离器性能的实验研究

结合水煤浆流化-悬浮燃烧的特点,通过全面测定循环流化床锅炉用旋风分离器在不同操作参数下的分离效率,研究了入口气速、入口颗粒浓度、入口颗粒物性等对旋风分离器的压降和分离性能的影响规律。实验结果表明,影响旋风分离器分离性能的主要物性参数是颗粒的中位粒径、密度,在入口颗粒的中位粒径相差较大时分离性能主要受粒径的影响,而当入口颗粒粒径相差较小时密度对分离器分离性能的影响则更为显著。     

Introduction and simulation of a small electro cyclone for collecting indoor pollen particles

Since pollen is a major cause of allergies, collecting it from the environment seems to be beneficial. In this study, a new electro cyclone is proposed and simulated for collecting pollen from indoor environments. In this cyclone, an electrode is added to a traditional cyclone to apply additional force to particles that have already been pre-charged. The obtained results showed an increase of 14, 33 and 53 (%) in separation efficiency for pollen particle sizes of 10, 8 and 6 µm. Moreover, at lower inlet velocity, high electrostatic voltage enhances the efficiency, with the effect being more noticeable on finer particles. The validity of the simulation results was confirmed by comparing it with experimental and simulation findings of our previous study. It is also concluded that small electro cyclone systems are more efficient in removing fine particles from various gas streams.