Separation Efficiency Of Cyclone Research Articles

Effect of Exhaust Pipe Size on Separation Efficiency of Cyclone Separator Used in Power Plant

In order to grasp the influence of exhaust pipe size on cyclone flow fields and improve the recovery and utilization rate of coal powder in power plant, the flow characteristics and the separation capacity of the fine coal powder separator in power plant were investigated through numerical simulation. The Reynolds stress model was employed to model the turbulent flow. The Eulerian-Lagrangian computational procedure was used to predict particles tracking in the cyclone. The particle trajectories were simulated using the discrete random walk. Five cyclone types with different insertion lengths of the exhaust pipe at the same other geometric dimensions were considered. It was found that tangential velocity played a dominant role in the radial distribution of particles, which was mainly represented by Rankine vortex. When the insertion length of the exhaust pipe was increased from 1638 mm to 5100 mm, the grade efficiency of 5–12 μm particles was increased by 19%, and the pressure drop reduced by 8%.

Effects of hyperboloid vortex finder and inlet angle on the cyclone flow pattern and separation efficiency

Gas-solid cyclone separators are widely employed within industrial contexts for the removal of particulate matter from gas streams. Recent research has unveiled the potential for enhancing cyclone performance by investigating the geometric implications of vortex finder (VF) configurations and inlet duct design. In this study, the influence of hyperboloid VF configurations and angled inlets on cyclone flow patterns and efficiency through a three-dimensional (3-D) computational fluid dynamics (CFD) methodology is examined. A high-turbulence flow has been modeled incorporating the Turbulence Reynolds Stress Model (RSM) in the commercial CFD software ANSYS Fluent. Dispersed phase particle trajectories and efficiency were computed by employing a Discrete Phase Model (DPM) based on the Lagrangian approach, with results closely aligned with experimental data for model validation. Cyclone performance was assessed in terms of pressure drop and separation efficiency across various geometric configurations. Our computational models revealed a tangential velocity range between 1.78 and 2.42 times the gas velocity at the inlet. Notably, hyperboloid-based designs demonstrated a remarkable 25.44% improvement in overall separation efficiency, while also experiencing a 16.95% increase in pressure drop compared to the base model. These findings clearly demonstrate the substantial improvement in cyclone performance achieved by the hyperboloid-based designs.

Numerical Simulation Study on Flow Field Characteristics and Separation Efficiency of Micro Cyclone by Shunt Ratio

In this study, based on the current situation of waste drilling fluid treatment, the operating parameters of micro cyclones are investigated. A 10-mm micro cyclone used to separate ultrafine particles was designed and the effect of the split ratio on the pressure and axial velocity in the micro cyclone as well as the total separation efficiency was investigated using CFD techniques. The conclusions obtained are that the pressure gradient in the microcyclone increases with the increase of the splitting ratio; the axial velocity decreases with the increase of the splitting ratio; the total separation efficiency increases with the increase of the splitting ratio.

Research on structural parameter optimization of a new axial inlet hydrocyclone separator based on response surface optimization method.

Aiming at the problem that the current hydrocyclone separator is affected by multiple structural parameters and there is interaction between the multiple structural parameters, it is difficult to determine the optimal structure. Taking the new axial inlet hydrocyclone separator as the research object, a fast parametric optimization method based on response surface optimization method is proposed. The overflow outlet diameter, overflow tube depth and small cone length, which have significant influence on the separation efficiency of the axial inlet hydrocyclone separator, are selected as the optimal variables, and the cyclone separation efficiency is selected as the response index. A mathematical driving model between the response index and the optimal variables is constructed by using the second-order polynomial basis function. The optimal structural parameters of the new axial inlet hydrocyclone separator are obtained through the response optimization of the parameter variables in the global response range through the mathematical driving model, and the numerical simulation method and laboratory test are double verified. The results demonstrated that the axial inlet hydrocyclone achieved the highest separation efficiency within the studied operational parameter range when the overflow pipe diameter was 6mm, the overflow pipe depth was 20mm, and the small cone length was 60mm. The separation efficiency improved from 89% to 93%. The rapid optimization of the structural parameters of the axial inlet hydrocyclone was successfully accomplished using the response surface optimization method.

Flowpattern in hydrocyclones, numerical simulations with experimental verification

This paper reports a detailed study of the flow in cyclone separators, with the use of most up to date computational fluid dynamics simulations, which are validated with positron emission particle tracking (PEPT) experiments tracing the movement of particles through the cyclone. The parameters varied were the viscosity of the carrier liquid, the flowrate and, in the numerical simulations, the inlet configurations of the cyclone, namely one and two inlets and, with the two inlets, a) both at right angles to the cyclone axis and b) angled downwards. The study reveals features of the flow, which have not been seen till now, but are necessary for the understanding and modelling of the separation and purification efficiency of cyclones. The results of the simulations and the close agreement with experiment are a testament to the reliability and accuracy of large eddy simulation (LES), even for flow features as difficult to simulate as the confined strongly swirling flows in cyclone separators. The results show that a contiguous, smooth surface of zero axial velocity does exist and has approximately the shape that has been assumed by modellers. The significant effects of fluid viscosity, underflow and modifications to the inlet are also shown.

Experimental Study on the Relation between the Energy Efficiency and Pressure Drop of Dual Inlet Cyclone Separator in Processing Indoor Farming Biomass Waste

The cyclone separator is a device commonly used to separate particles from air, gas, or liquid streams. The addition of a secondary inlet is aimed at enhancing separation efficiency and productivity. This study aimed to investigate the relationship between energy efficiency and pressure drop in dual inlet cyclone separators. The cyclone separator was intended to be used in processing biomass waste from indoor farming. The experiment was conducted by varying the input velocity of the system and injecting sand particles into the cyclone separator. The results showed that energy efficiency is positively correlated with average particle size and negatively correlated with pressure drop and velocity. The highest energy efficiency was observed when using particles with a size of 624µm and an input velocity of 9 m/s. These findings suggest that optimizing particle size can lead to reduced energy usage and operational costs while minimizing environmental pollution. The present study provides a comprehensive understanding of the relationship between energy usage and efficiency in a cyclone separator, which can help industries improve their performance.

Evaluation of the PANS method for the prediction of the fluid flow in a cyclone separator

The simulation of the cyclone separation efficiency can rapidly become very expensive in time of calculation, which is not suitable for industrial application. The prediction of the complex turbulent gas flow inside a cyclone is necessary to estimate its pressure drop, its characteristics and finally its separation efficiency. Even though classic models such as RSM and LES can effectively predict such type of flow, the quality of the results and the computation cost can be discussed. In this work, Partially Averaged Navier–Stokes (PANS) method is proposed to simulate the fluid flow inside a gas cyclone. Compared to experimental and numerical results of a literature review, this model predicts reasonably the time-averaged tangential and axial velocity fields, and more accurately the pressure drop across the cyclone in shorter CPU times. The sensitivity of the PANS approach to the unresolved to total kinetic energy ratio f k was also evaluated with two different definitions. The first one was the standard definition developed by Girimaji et al. [1] and the second one was based on a statistical equivalence between the DES and PITM. The proposed model offers a better cost to quality ratio compared to the classic RANS approach.

Parametric and General Evaluation of Mathematical Models Used for Critical Diameter Determination in Cyclone Separators

Cyclone separators are used in multi-phase flows for phase separation or classification. Pressure drop and separation efficiency are essential parameters for determining the performance of a cyclone separator, and critical diameter is an important parameter related to cyclone separation efficiency. In this study, we investigate the critical diameter prediction ability of various mathematical models; in particular, approximately 400 experimental data available in the literature, reflecting different geometries and operating parameters, are used to investigate the critical diameter prediction ability of the selected models. These data are calculated using ten mathematical models selected among the most widely used models which operate based on different principles, and the associated critical diameter values are determined. These calculated values are then compared with those obtained in the experimental studies. As a result, there are many parameters affecting the performance of cyclone separators. The fact that some of these parameters are not used in the models can lower the prediction accuracy of the model, depending on the context. For this reason, the parameters for which the models give better results are analyzed in detail. According to these results, users can choose a model more appropriately. In addition, an absolute evaluation is provided, demonstrating that the models provide important ideas regarding cyclone performance.

Performance analysis of a gas cyclone with a converging-diverging vortex finder

In this study, the influence of a novel converging-diverging (CD) vortex finder on the performance of a gas cyclone was studied using the computational fluid dynamics (CFD) method. In addition, the influence of the CD outlet pipe on the erosion rate of the cyclone was investigated. The cutoff diameter, pressure drop, and erosion rates of the new vortex finder design were compared with those of the conventional straight outlet pipe cyclone. The throat of the CD pipe was at the same level as the cyclone's roof. The simulation showed that the CD outlet pipe significantly reduced the cyclone pressure drop. The height and diameter of the converging part of the vortex finder affected the cyclone pressure drop and separation efficiency. Increasing the converging part's inlet diameter reduced the outer vortex tangential velocity and the cyclone separation efficiency. Increasing the converging part inlet diameter reduced turbulent intensity at different cyclone levels. The CD vortex finder with the shortest height and inlet diameter of the converging part (model C1) reduced the cutoff diameter from 6.2 µm to 5.9 µm. The CD outlet pipe with the largest height and inlet diameter of the converging part (model C6) reduced the pressure drop by 42.2% compared to the conventional cylindrical vortex finder. The erosion rate also decreased significantly with an increase in the converging part inlet diameter. However, the converging part height only slightly affected cyclone performance.

A Numerical Approach to Characterize the Efficiency of Cyclone Separator

Cyclone separators are active filtering devices suitable for a variety of industrial applications from conventional cutting oil pumps to recycling liquids. Since the vortex flow inside cyclones is highly complicated, the performance and flow patterns of these filters should be thoroughly researched. Liquid–solid cyclones mostly use water. Numerical studies on cyclones using higher-viscosity oils are limited. In this study, a liquid–solid cyclone injected with medium-viscosity cutting oil containing various sized-particles was comprehensively investigated. The reliability of computational fluid dynamics (CFD) methods was verified through a comparison with the experimental results. Three models with different geometries were considered for the analysis. One model was used for CFD verification. The other two models involved adding sockets for hopper length extension and changing the shape of the bottom of the hopper. The models that changed the shape of the hopper, thus directly affecting the cyclone performance, were investigated, and each model was qualitatively compared using a validated method. In addition, particle separation efficiency was evaluated by focusing on the velocity distribution to quantitatively confirm the influence of changing the shape of the hopper. The tangential velocity was determined to be similar across all three models, while the axial velocity was different and the change in the velocity of transport of the particles affected the filter function.

Modeling and Analysis of Cyclone Separation Efficiency Based on Spacecraft Heat Pump System

Modeling and Analysis of Cyclone Separation Efficiency Based on Spacecraft Heat Pump System

Numerical investigation on dynamic characteristics of flow field in cyclone separators with different dust hopper structures

The dynamic characteristics of flow field in cyclone separators with different dust hopper structures were studied by coupling Reynolds Stress Model (RSM) and Lagrangian Particle Tracking (LPT) methods. The characteristic frequencies of cylinder section, cone section and dust hopper were calculated as f1 = 53 Hz, f2 = 65 Hz, and f3 = 8 Hz by using Fast Fourier Transform (FFT) method, respectively. Based on the effects of f3 on the motion of vortex, the separated space was divided into none affected region, weakly affected region, and strongly affected region. The characteristic frequency of dust hopper increased with the decrease of dust hopper diameter, while it was independent of the height. The dust hopper with d = 1.5D (model D3) and h = 1.5D (model H3) can significantly decrease the effect of back-mixing on the motion of inner vortex, which is beneficial to improve the efficiency of cyclone separator.

Numerical investigation on the swirling vortical characteristics of a Stairmand cyclone separator with slotted vortex finder

The slotted vortex finder (SVF) represents a novelly modified cyclone vortex finder, which is validated to be valuable and prospective for industrial applications. The main purpose of present study is to illustrate the effect of slotted vortex finder on the swirling turbulent flow characteristics of cyclone separator in comparison with conventional vortex finder (CVF). Based on three cyclone models (CVF, SVF_D1, SVF_D2), the differences of swirling vortical characteristics between SVF and CVF models are comprehensively tested and the influence of SVF insertion length on the cyclone performance was discussed. The overall detailed features and variations of flow pattern, such as velocity profile distribution, unsteady particle tracking, swirl number comparison and special flow phenomena of vortex eccentricity in the whole cyclone separator body, are analyzed in detail. Specifically, The SVF_D2 model could improve the cyclone separation efficiency (about 20% reduction of pressure drop and 4.2% reduction of cut off size) and also reduce 40% of central vortex rotation frequency compared with CVF model at vin = 16.1 m/s. The current study is beneficial to further clarify the influence of SVF on the mechanism of the particle separation motion in cyclone separator and identify the characterization differences between traditional cyclone separator and cyclone with installation of SVF.

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%.

Forming and breaking the ceiling of inlet gas velocity regarding to separation efficiency of cyclone

The maximum-efficiency inlet velocity (MEIV) is a ceiling of inlet gas velocity that defines separation efficiency during cyclone design and operation. Experiment and computational fluid dynamics (CFD) simulation exhibited that an apex cone at the dust outlet can break the ceiling and improve the separation efficiency. The phenomenon is closely related to the effect of excessive high inlet gas velocity on the back-mixing escape of fine particles, which is the final result of back mixing, entrainment by the rapid upward airflow, and secondary separation of the inner vortex. In the center of the inner vortex, the airflow rotates slowly and moves rapidly upward. This elevator type of airflow delivers re-entrained particles to the vortex finder. A higher inlet gas velocity accelerates the elevator, causing more entrained particles to escape. This explains the decrease in efficiency at an excessively high inlet gas velocity. When an apex cone is installed at the dust outlet, the back-mixing is significantly weakened because the vortex core is bounded to the center of separator, while the transport effect of rapid upward airflow is weakened by the decrease in axial velocity in the center. Therefore, particle escape is weakened even at excessive high inlet gas velocities. Instead, the centrifugal effect is enhanced because of increased tangential velocity of the gas and particles. Consequently, the ceiling of inlet gas velocity is broken.

Effect of erosion rate and particle mass loading on separation efficiency of square cyclone by considering gas temperature

Effect of erosion rate and particle mass loading on separation efficiency of square cyclone by considering gas temperature

Effects of different cylinder roof structures on the vortex of cyclone separators

To improve the internal flow field of a cyclone separator, grasp the effects of the cylinder roof structure on the flow field of the cyclone separator, and improve the separation efficiency, the research on the influence of different cylinder roof structures on the vortex of the cyclone separator was carried out. Through numerical simulations, the gas flow was simulated using the Reynolds stress model (RSM). The vortex of the cyclone separator captured by the Q criterion and Ω-method were compared. Based on the Ω-method, the vortex and separation efficiency of cyclone separators with three different cylinder roof structures were analyzed. The results show that compared with the Q criterion, the Ω-method captures the non-fractured iso-vortex surface inside the exhaust pipe, and can more accurately capture the vortex inside the cyclone. The iso-vortex surface of an Arc-shaped Cylinder Roof (ACR) cyclone separator has a smaller curvature, better continuity, and less distortion than that of a Flat Cylinder Roof (FCR) cyclone separator and Wedge-shaped Cylinder Roof (WCR) cyclone separator. The vortex lines and vorticity magnitude curves of the ACR cyclone separator are more regular, uniform, and symmetrical than those of the FCR cyclone separator and WCR cyclone separator. Compared with the FCR cyclone separator, the tangential velocity inside the ACR cyclone separator and WCR cyclone separator is greater. The positive radial velocity near the wall of the cylinder cone inside the ACR cyclone separator and WCR cyclone separator is greater. For the ACR cyclone separator and WCR cyclone separator, the positive axial velocity at the top of the cylinders, outside the wall at the lower end of the exhaust pipes, and near the wall of the cylinder cones is greater. The streamlines inside the ACR cyclone separator and WCR cyclone separator are more gentle and regular. For the ACR cyclone separator and WCR cyclone separator, the gas at the top of the cylinders flows obliquely downward along the roofs, which helps to suppress the top ash ring and short-circuit flow and improve the separation efficiency. Compared with the FCR cyclone separator, the separation efficiency of the ACR cyclone separator and WCR cyclone separator is increased by 24.66% and 14.06%, respectively. The research results provide useful guidance for the improvement of the cylinder roof structure and a reference for improving the flow field and separation performance of cyclone separators.

CFD study on the effect of gas temperature on the separation efficiency of square cyclones

CFD study on the effect of gas temperature on the separation efficiency of square cyclones

A low-cost solution for the collection of fine particles in square cyclone: A numerical analysis

Generally, the square cyclone separator suffers from low separation efficiency. Therefore, a deeper investigation for developing an effective method to enhance this type of cyclone's overall performance is of interest. Although different methods are available, optimizing the vortex finder's shape for enhancing separation efficiency is a low-cost solution. The present study assesses the effect of vortex finder on the performance of a square cyclone, thus guiding the design for improving the square cyclone separation efficiency. Three different vortex finders namely, cylindrical, convergent, and divergent, are studied. A series of 3D numerical simulations are carried out by solving the Reynolds-Averaged Navier-Stokes equations with the Reynolds Stress Model (RSM) and performing the Eulerian-Lagrangian particle tracking analysis. The results demonstrate that using a convergent vortex finder improves the square cyclone's separation efficiency while producing an increase in pressure drop. Using a convergent vortex finder is beneficial for reducing the 50% cut-size. Among all vortex finders, the convergent one with vortex finder diameter ratio (D2/D1 = 0.75) allows the square cyclone to collect finer particles. As a result, the 50% cut size decreases by approximately 33% at an inlet velocity of 28 m/s.

Performance improvement of a cyclone separator using different shapes of vortex finder under high-temperature operating condition

In the present study, the effect of inlet temperature on cyclone performance was numerically investigated based on computational fluid dynamics (CFD) approach. The Eulerian–Lagrangian approach in conjunction with the Reynolds stress transport model was employed to solve the unsteady Reynolds-averaged Navier–Stokes equations. A series of numerical simulations were carried out at a wide temperature range of 293 K to 700 K. Conclusive results indicated that the separation efficiency of cyclone significantly decreased with any increment of inlet temperature due to weaker swirling flow across the cyclone at a higher temperature. In this condition, it is essential to find an impressive way to overcome this negative effect. Hence, four proposed shapes, namely divergent vortex finder and convergent vortex finder (CVF) were designed to use instead of base one under high-temperature operating conditions. The results extracted from CFD simulations demonstrated that the maximum tangential velocity was obtained about 2.2 times of the inlet velocity (v = 11.99 m/s) at T = 700 K for cyclone with CVF 1, while it was predicted 1.9 times of the inlet velocity for a base cyclone. Moreover, other cyclones generated tangential velocities even less than the base cyclone. Higher tangential velocity led to increase the centrifugal force and cyclone separation efficiency. Using CVF 1 instead of a base vortex finder significantly helped the cyclone to collect finer particles. Whereas the separation efficiency enhanced 9.5% for the particle size of 2 µm at T = 700 K and v = 20.18 m/s compared to the base cyclone.