Axial Cyclone Separator Research Articles

Determination of an axial gas cyclone separator cut-off point by CFD numerical modeling

Determination of an axial gas cyclone separator cut-off point by CFD numerical modeling

Numerical Study of the Gas–Solid Separation Performance of Axial Flow Cyclone Separators

Cyclone separators, which have a high separation performance, play a crucial role in mitigating the occurrence of dust explosion incidents. This study aims to improve the performance of an axial cyclone separator using the results of simulations employing the RNG k-ε model together with a user-defined function to simulate the wall collision process. The effectiveness of various structural modifications to the vortex tube has been addressed. Specifically, we found that increasing the number of blades, reducing the blade exit angle, and adopting L-shaped blades increase separation efficiency. Additionally, enlarging the guide vane and exhaust pipe diameters, as well as increasing the exhaust pipe inclination angle, contribute to an improved separation performance due to the developed tangential velocity and vortex cores. However, it also increases the pressure drop losses due to the increase in the turbulence pulsation entropy and the wall entropy, while the time-averaged entropy is found to be less significant. As a result, our study sheds light on the flow characteristics, the gas–solid separation process, and the energy loss mechanism in the cyclone separator.

Experimental investigation on the separation characteristics of the novel combined separator

The cyclone separator is widely used as the efficient steam separation device for the nuclear reactor. In this study, a novel gas–liquid separator that can realize efficient and stable gas–liquid separation under a wide range of working conditions is designed. The separator is organically combined with an axial cyclone separator and a tangential cyclone separator. The axial cyclone separator performs the role of rectification and pre-separation, and the tangential cyclone separator ensures separation performance. The variation in the gas–liquid interface characteristics and separation characteristics of cyclone separation under different inlet flow rates are investigated. Compared with the single tangential cyclone separator, the separation deterioration range of the novel separator is significantly reduced. The addition of the pre-separator effectively broadens the operating conditions for efficient separation. The pressure drop of the novel separator is reduced by more than 50 %. Based on the separated flow model, the relationship between the separation pressure drop ratio and dimensionless number is established, and the prediction method for the pressure drop is put forward with the prediction accuracy within ±10 %, which provides reference for the practical application of the novel separator.

Experimental investigation on separation characteristics of axial cyclone separator

Experimental investigation on separation characteristics of axial cyclone separator

The effect of a counter cone on the performance of an axial cyclone separator

The effect of a counter cone on the performance of an axial cyclone separator

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.

A Study on the Erosion Mechanism of an Axial Cyclone Separator for Gas Purification

Severe erosion occurs in the cone bottom and the joint part between the cone and cylinder of the cyclone separator used in high-pressure natural gas transportation. The main objective of this study is to reveal the mechanism and influencing factors of erosion. To address these issues, the numerical simulations were used to investigate the parameters, such as inlet gas velocity, particle concentration, particle size, the cone length, the diameter of dust exit and the vortex finder. The results indicate that wall erosion is significantly affected by the inlet gas velocity and particle diameter. Increasing the cone length and the dust exit diameter can effectively reduce wall erosion, whereas the cyclone separation efficiency would be reduced simultaneously. It is worth noting that the vortex finder with spiral slits is of benefit to increase the cyclone separation efficiency but decreases the maximum erosion rate of the cyclone cone by at least 80%.

The multi‐objective optimization of an axial cyclone separator in the gas turbine

Herein the multi-objective optimization of an axial cyclone separator is performed to enhance the overall performance with different velocities. And the separation efficiency and pressure drop are expected as the objective functions. In this paper, the difference value between internal and external blade outlet angles is regarded as one of the parameters to optimize. The regression expressions, which are obtained by Box-Behnken Design and the two-fluid model, are used in Nondominated Sorting Genetic Algorithm II to maximize separation efficiency and minimize pressure drop. It is found that the separation efficiency has a peak value with the rise of inlet velocity, and the response degrees of the internal angle, difference of the two angles, and blade number is disparate at different velocities. The pressure drops of the optimal axial cyclone tubes are smaller than the initial ones, but the separation efficiency is almost the same. Meanwhile, the accuracies of the optimization and numerical results are verified by the experiments. For the samples in 3, 5, and 7 m/s, pressure drop can be reduced by 24.1%, 22.7%, and 34.3% respectively. The simulation results indicate that the radial pressure difference and swirl number have been reduced. Besides, the optimal designs have more stable and even near wall particle distribution after multi-objective optimization.

Numerical simulation of the particle-wall collision strength and swirling effect on the performance of the axial flow cyclone separator

Abstract The axial cyclone separator has simple structure, operates to reducing dust concentration in grain storehouses, and features low production cost, and convenient installation. Aiming to obtain the separation characteristics of an axial flow guide separator, the particle wall collision and the performance of multi-tubes were simulated with Fluent. The renormalization group (RNG) k − ε model was used to study the turbulent modeling and the user define function (UDF) was used to calculate the particle-wall collision. The simulation and experimental results were compared to verify the computation model. The results showed that the basic feature of the flow pattern remains stable and the separation efficiency of 800 kg/m3 particles is higher than 2650 kg/m3 particles when the inlet velocity increases from 2 to 5 m/s. When the inlet velocity was 5 m/s, the normal velocity restitution ratio had a significant effect on the efficiency, the separation efficiency of 167 μm particles changed from 76.74 to 97.93% and a smaller normal velocity restitution ratio had a higher the efficiency. In comparison, the efficiency remained unchanged when changing the tangential velocity restitution ratio. Furthermore, the effects of three target wall materials on the separation efficiency were investigated. And the simulated efficiency the of 296 μm particle of 2024 aluminum, 410 stainless steel and Ga1–4V titanium were 82.15, 79.52 and 77.53% respectively. Besides, effects of tube diameter on performances of cyclone separator were discussed and high intense collisions between particles and walls may occur in a small diameter of cyclone tube, causing deteriorated separation performance. Moreover, with the addition of the dust chamber, the efficiency of cyclone used in combination is slightly improved since the vortex in the exhaust pipe has been finely changed.

Comparison of models to predict the collection efficiency of an axial cyclone with a spindle vane

An axial cyclone separator with a spindle vane has the advantages of low pressure drop and high collection efficiency. Collection efficiency is an important parameter for assessing the performance of a cyclone separator. Previous studies have shown that as the number of turns of a spindle vane increases or the pitch of the spindle vane decreases, the collection efficiency of the axial cyclone separator increases. There are two models for predicting the collection efficiency of an axial flow cyclone. One model by Hsiao et al. (2011) can predict the collection efficiency if the primary dimensions and inlet flow conditions of the cyclone are given. But the other model by Hsu et al. (2005) additionally requires a fitting constant to determine the collection efficiency. Because the accuracy of the model of Hsu et al. (2005) is limited by the fitting constant, it is necessary to find a fitting constant systematically. In the present study, we developed a method to determine the fitting constant for the model of Hsu et al. (2005) through experimental, numerical, and analytical investigation. It was found that the fitting constant is the function of flow transit time in the vane section. Finally, we compared the two existing prediction models with each other. Both model predictions agreed well with the experimental data.

The use of axial cyclone separator in the separation of wax from natural gas: A theoretical approach

The waxy component in natural gas may bring about some challenges in the treatment and transportation processes, especially in the cryogenic separation process. An axial flow cyclone separator was applied to separate wax from natural gas. An Eulerian–Lagrangian approach combined with the Reynolds stress model (RSM) was adopted to investigate the flow of gas and wax droplets in the separator. The distributions of static pressure as well as tangential, axial, and radial velocity were presented to describe the flow field in the cyclone separator. The results suggested that the established model could be used to simulate the separation process in the cyclone efficiently. Most importantly, the simulation was conducted under various inlet velocities and mass content of waxy component to study the effects of the operation parameters on separation efficiency. It was indicated that the inlet velocity has a great impact on the separation efficiency when it is greater than 15 m/s. The effect of mass content of waxy component is significant when it is smaller than 172.4 kg/m3, especially for small sized wax droplets. It is believed that the separation efficiency in the proposed axial flow cyclone is as high as 95% with suitable operational conditions.

Numerical study on pressure drop and filtration efficiency of gas–solid flow through axial cyclone separators

The separation of particulate matter from incoming gas flow is necessary for different industrial applications, and this filtration process is primarily done by cyclone separators. In axial inlet cyclone separators, a swirling motion is imparted to the incoming flow by means of a swirl generator and particle separation is achieved by centrifugal separation. In this paper, the gas-particle flow through an axial inlet cyclone separator is analysed by the Eulerian–Lagrangian CFD approach using the open-source package OpenFOAM. The turbulent flow field is modelled using Reynolds-averaged Navier–Stokes equations with RNG k–e model, and the particle trajectory is calculated by discrete phase modelling. The study mainly focuses on the modelling and simulation of the dispersed flow, the development of the turbulent flow field inside the cyclone filter and the influence of the solid phase on the flow field. The simulation results show that the solver effectively models the flow field and the centrifugal separation of particles. The analysis of particle trajectory and the effect of particle density on the flow with both uniform and varying inlet particle distribution are also discussed.

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.

Numerical analysis of multiphase flow through axial vortex tube cyclone separators

Axial cyclone separators are used as primary filtration components in many internal combustion engine applications. A numerical study of gas-solid flow through an axial cyclone separator is carried out by Eulerian-Lagrangian CFD approach, which uses discrete phase modelling (DPM) of particles and solution of incompressible turbulent Navier-Stokes equations with RNG k—ɛ closure model. The effective filtration of inlet air from dust particles is an important requirement for prolonged engine life cycle. In axial cyclone separators, a helical swirl generator is used for imparting swirling motion to theparticle laden flow and particles are filtered by centrifugal separation and then scavenged using a vortex tube. In the present work, the modelling done in OpenFOAM successfully captures the features of the swirling flow, along with particle–gas and particle–wall interactions for a varying size distribution at the inlet. Studies were aimed at analysing the effect of particles and its effect on improving the performance of the filter.

Numerical analysis of cocurrent conical and cylindrical axial cyclone separators

Axial concurrent liquid-liquid separator is seen as an alternative unit to the traditional tangential counter current cyclone due to lower droplet break ups, turbulence and pressure drop. This paper presents the numerical analysis of a new conical axial cocurrent design along with a comparison to the cylindrical axial cocurrent type. The simulation was carried out using CFD technique in ANSYS-FLUENT software. The simulation results were validated by comparison with experimental data from literature, and mesh independency and quality were performed. The analysis indicates that the conical version achieves better separation performance compared to the cylindrical type. Simulation results indicate tangential velocity with 8% higher and axial velocity with 80% lower recirculation compared to the cylindrical type. Also, the flow visualization counters shows smaller recirculation region relative to the cylindrical unit. The proposed conical design seems more efficient and suits the crude/water separation in O&G industry.

Experimental and Numerical Study on the Resistance Performance of an Axial Flow Cyclone Separator

The purpose of this paper is to study the pressure drop of an axial flow cyclone separator as a function of inlet velocities using experimental and computational fluid dynamics (CFD) methods. First, the resistance performance of the separator was acquired under ambient pressure and temperature with little change by wind tunnel experiments. Then, numerical simulations were carried out in CFD code Fluent 6.3 under standard operating conditions. A comparison between the experimental and CFD data demonstrates that the CFD method can predict the pressure drop of the axial cyclone separator excellently. Additionally, the results show that the axial flow cyclone separators have a pressure drop coefficient of approximately 7.5. To study the effect of ambient pressure and temperature on pressure drops, the same CFD method was employed to predict the resistance performance under various operating conditions. Then the numerical results were compared with the data of a normalization process method of pressure drops raised in this paper. Their comparison demonstrated that the normalization method had a high precision in predicting the influence of ambient operating parameters on pressure drops of an axial flow cyclone separator.

Effect of Blade Numbers on Pressure Drop of Axial Cyclone Separators by CFD

In this article, computational fluid dynamics(CFD) method is used to predict the effect of blade numbers on the pressure drop of axial cyclone separators. A three-dimensional model is built to acquire the resistance of axial cyclone separators with different blade numbers. The flow field inside cyclone separators is calculated using 3D Reynolds-averaged Navier-Stokes equations. And turbulence model is used to simulate the Reynold stress. Also pressure drop of cyclone separators with different blade numbers is expressed as a function of different inlet velocities. At the same inlet velocity with increasing the blade numbers, pressure drops of cyclones reduce greatly. And changing the blade number of cyclone separator is an effective method to improve its resistance performance.

A Fluid Mechanics Model for an Axial Cyclone Separator

The design of an axial cyclone for the removal of liquid droplets from a liquid stream is considered. The design constraints are that the swirl in the separation section is to be maximized and that an adverse pressure gradient in the flow is to be avoided everywhere in order to prevent droplet breakup. First, a simplified expression is derived for the separation efficiency, defined as the maximum length needed to remove droplets or particles form the flow. The result shows that it is advantageous to position the vanes that generate the swirl at a radius larger than the section where actual separation takes place. This leads to a design in which the swirl generator is mounted on a central body positioned in a wider section of the pipe than the separation section. To calculate the flow and the pressure field in this cyclone geometry, the authors develop a stream function method which uses a superposition of axisymmetric sources and sinks. They show by means of an example that they can indeed design a geometry in which the undesirable adverse pressure gradients is avoided.