Cyclone Performance Research Articles

Cyclone dimensionless pressure drop, cut size, and separation slope: One dimensionless number (Reynolds) to rule them all

The flow field and performance characteristics of the high-efficiency Stairmand cyclone have been computationally investigated at a wide range of Reynolds numbers Reout = 84 − 252876 by varying the cyclone diameter, inlet velocity, operating temperature and pressure using the LES simulations. The effects of these parameters on the dimensionless cyclone performance characteristics (Euler number, square root of Stokes number and slope of the transformed grade efficiency curve) and dimensionless lip flow and lip velocity have been revealed. Five critical Reynolds numbers which correspond to the transition between different regimes and sub-regimes have been determined. All three dimensionless cyclone performance characteristics and two lip flow characteristics are ruled by the Reynolds number.

CFD-based redesign of large industrial-scale cyclones

Cyclones represent a cost-effective solution employed for the separation of particles in gas-solid streams, wherein the enhancement of performance relies on the careful balance between pressure drop and collection efficiency. This study employs Computational Fluid Dynamics (CFD) techniques to numerically assess a large-scale first stage cyclone within a cement kiln cyclone tower. Investigating its reported low collection efficiency, we analyze the impact of geometric modifications aimed at enhancing cyclone performance. The introduction of a dipleg proves to be particularly effective, leading to a substantial increase in collection efficiency and a reduction in pressure drop. The most favorable cyclone configuration demonstrates a remarkable 6 % improvement in collection efficiency and a decrease in pressure drop of approximately 1 mbar. Consequently, particle emissions from the first-stage cyclone are reduced by approximately 30 %, while an increase in clinker production by approximately 100 tons per day is achieved. These findings showcase the potential for significant operational and environmental benefits through optimized cyclone design in cement manufacturing processes.

Mechanistic study and structural optimization for the improvement of flow field in cyclone annular space with bypass flow

The inefficiency of cyclone separation for fine particulate matter is attributed to the presence of longitudinal circulating flow and short-circuit flow in the annular space. To enhance cyclone performance, a novel cyclone design called enhanced cyclone with split flow (ECSF) has been developed, which effectively suppresses circulating flow, short-circuit flow, and eccentric circulation through bypass flow and underflow. The mechanism of bypass flow on improving the annular space’s flow field is investigated using the Reynolds stress model and discrete phase model, along with an examination of the impact of annular space height. Simulation results demonstrate that bypass flow can directly counteract vertical circulation in the annular space by creating a gas partition near the vortex finder inlet to block short-circuiting. This suppression effect on both vertical circulation and short-circuiting increases with higher bypass flow ratios. Furthermore, while the presence of an annular space limits ECSF performance optimization, its elimination simplifies structure by removing the vortex finder while maximizing separation efficiency. When no annular space exists (height = 0 mm), ECSF achieves highest separation efficiencies for 10 μm and 2.5 μm particles at approximately 96 % and 83 %, respectively; energy consumption is also minimized at only 0.94 kPa. These findings lay a foundation for future application research on ECSF.

Comparison of experimental, empirical, and CFD pressure losses of lab-scale sampling cyclones

Significant efforts remain to be undertaken to achieve efficient separation of particulate matter. Devices widely used for this purpose are cyclone separators. This study investigates the pressure loss phenomena and flow structures within cyclone devices, aiming to elaborate and optimize their performance. Traditional cyclone models: (i) Muschelknautz, (ii) Stairmand, and (iii) PM1 Sharp Cut, are evaluated alongside the innovative vortex limiter cyclone (VL) to distinguish their advantages and limitations. The focus is on describing the relation between pressure loss and flow characteristics of the different cyclones with the same design separation diameter of 1μm. Empirical pressure loss correlations analyze how pressure losses vary within different cyclone devices. It was proven that predictions depend on cyclone size and operational parameters. Computational Fluid Dynamics (CFD) simulations further elucidate pressure loss mechanisms, highlighting the complexities inherent in modeling cyclonic behavior accurately. In conclusion, this study contributes to advancing the understanding of cyclone performance by elucidating the intricate interplay between pressure loss phenomena and flow structures. Such insights hold profound indications for optimizing cyclone separator design and operation in diverse industrial applications.

Effect of inlet water vapor mass fraction on flow characteristics in Laval nozzle

Abstract The Laval nozzle is an important component of the supersonic cyclone to achieve the change of gas–liquid two-phase, and the condensation characteristics of the Laval nozzle have an important influence on the separation performance of the supersonic cyclone. In this work, the effect of inlet water vapor mass fraction on the condensation characteristics in the Laval nozzle was investigated using numerical simulation and experimental methods by establishing a three-dimensional numerical model of air-water vapor supersonic condensation flow. The flow field structures in the Laval nozzle under different inlet water vapor mass fractions were investigated, including Mach number, pressure, and temperature and the effects of the inlet water vapor mass fraction on the liquefaction characteristics in the Laval nozzle were investigated. In addition, the droplet distribution in the Laval nozzle were also tested by a particle image velocimetry (PIV) experimental system. The comparison of simulation and experimental results indicates that the numerical model established in this work can effectively describe the real flow situation in the Laval nozzle. The results show that the inlet water vapor mass fraction has a little effect on the flow field structure in the Laval nozzle, and has the significant impact on the water vapor condensation characteristics. With increasing the inlet steam mass fraction from 5 % to 12.5 %, the nucleation rate, droplet number, and separation efficiency in the Laval nozzle increase to 4.05 × 1021 kg−1 s−1, 3.67 × 1014 kg−1, and 79.4 %, respectively, and when further increasing the inlet steam mass fraction to 15 %, these parameters decrease.

Design and Analysis of Gas Cyclone with Arc-Shaped Cone Using Bézier Curve for Improved Performance

Abstract The research investigates novel gas cyclone separators with curved conical sections, comparing eight configurations with varying curvature sizes. Gas cyclones are traditionally used as particle separators to remove dust from gas streams, aiming to achieve a dust-free gas flow at the exit pipe while recovering particles to the dust outlet. Computational fluid dynamics (CFD) was employed to model the gas cyclone using the Reynolds stress turbulence model (RSM); the study examines flow fields and pressure losses. It finds that increased curvature correlates with reduced pressure drop. The curved profile is derived from the Bézier curve, characterized by a set of control points determining its shape. This study examines eight cyclone configurations with the intermediate point placed at varying fractions of the main radius: 1/8, 1/4, 3/8, 1/2, 5/8, 3/4, 7/8, and the main radius itself. The investigation focuses on the impact of different conical segment shapes on cyclone performance, highlighting how convex variants outperform others at higher flow rates while concave variants exhibit higher pressure drop. The pressure drop in the convex variant with an intermediate point position equal to the main radius decreased by 50%. These findings suggest the potential of the convex variant in certain operating conditions over traditional designs with improved particle capture efficiency.

Numerical analysis of cyclone separators with unique Dipleg structures at different Dipleg-to-dustbin ratios

This study investigates the influence of various configurations of dipleg and dustbin structures on cyclone separator performance. For comparative analysis, the inverted cone dipleg which reported has the highest collection efficiency was employed, and six models were developed with varying dipleg-to-dustbin ratios while maintaining a constant total height. Unsteady simulations were conducted using the RSM model and the Eulerian-Lagrangian approach to analyze the flow dynamics and particle migration behaviors in cyclone separators. The increase in dipleg length significantly influenced flow behavior in both the dipleg and dustbin regions, initially resulting in increased flow complexity before transitioning to smoother and more regular patterns. Analysis of vortex frequency indicated a weakening back-mixing effect with increased dipleg length, further underscoring the impact of this parameter on cyclone performance. Quality factors under different particle size ranges are proposed to compare the separation efficiency and pressure drop of different models, providing a reference for the selection of cyclone in different application scenarios.

Performance and techno-economic evaluation of a high-efficiency electrospray cyclone

"Nowadays, because of the global air pollution issue caused by fine dust, fine dust collection and removal technologies are crucial for enhancing living environments and human health. This research proposes a new pilot-scale electrospray cyclone (ESC) designed for the collection of submicron dust particles. The experimental apparatuses comprised a cyclone dust collector and an insulating tank. Initially, laboratory-scale single-nozzle visualization tests were conducted to investigate the droplets’ number and size under various operating conditions. Subsequently, based on the visualization research outcomes, electrospray module was inserted to the industrial cyclone, which was designated by ESC. Performance assessments of the pilot-scale ESC were conducted under diverse water flowrates, applied voltages and nozzle sizes. The capture efficiencies for PM10, PM2.5, and PM1.0 were measured up to 98.2%, 95.4%, and 90.3%, respectively. Both the environmental and economic viabilities of the newly-proposed ESC in this study were evaluated based on three aspects: 1) capacitive particle collection efficiency; 2) capacitive installation cost; and 3) rated power and operational cost. This evaluation method has been defined as the Levelized Cost of Precipitator (LCOP), and it is intended to assess the environmental and economic performance of 5-convenstional dust collectors. In these results, the ESC shows relatively high performance in terms of the environmental and economic aspects. Based on these indices, we assess that the ESC has one of the promising alternatives of commercial precipitators."

The impact of operating temperatures on the fluctuating flow field and precessing vortex core in cyclone separator using large-eddy simulations

The present study evaluates numerically the impact of the operating temperature of gas on the cyclone performance viz. the pressure drop, collection efficiency, and flow field details at an inlet velocity, Uin=15 m/s. The gas temperature in a range of 273–1073 K is considered to significantly vary the fluid density and viscosity. For an in-depth analysis, we use advanced closure large-eddy simulation (LES) with the standard Smagorinsky model for treating the unresolved scales. LES can accurately provide additional details on the precessing vortex core phenomena that give rise to enhanced fluctuations in the core region of the cyclone. Apart from the traditional fast Fourier transformation analysis to evaluate the periodicity in the signal, we also perform continuous wavelet transformation and empirical mode decomposition operation on the temporal velocity signals for a better understanding of the flow instabilities—the signals reveal variations of frequency components with time, indicating a non-stationary behavior. It has been observed that an increase in the gas temperature causes lateral contraction of the inner vortex followed by the reduction in its precessional frequency about the cyclone axis with a significantly increased level of noise in the spectra. Furthermore, both pressure losses and collection efficiency largely reduce due to the weakening of swirling strength and enhancement in the fluctuating velocity components with an increase in the gas temperature.

Multi-Objective Optimization of Cyclone Separators Based on Geometrical Parameters for Performance Enhancement

The present study focuses on performing multi-objective optimization of the cyclone separator geometry to lower the pressure losses and enhance the collection efficiency. For this, six geometrical entities, such as the main body diameter of the cyclone, the vortex finder diameter and its insertion length, the cone tip diameter, and the height of the cylindrical and conical segment, have been accounted for optimization, and the Muschelknautz method of modeling has been used as an objective function for genetic algorithms. To date, this is one of the most popular mathematical models that accurately predicts the cyclone performance, such as the pressure drop and cut-off particle size. Three cases have been selected from the Pareto fronts, and the cyclone performance is calculated using advanced closure large-eddy simulation—the results are then compared to the baseline model to evaluate the relative improvement. It has been observed that in one of the models, with merely a 2% reduction in the collection efficiency and an increase of 12% in the cut-off particle size, more than a 43% reduction in pressure drop value was obtained (an energy-efficient model). In another model, a nearly 25% increment in the collection efficiency and a reduction of 42% in the cut-off particle size with a nearly 36% increase in pressure drop value were observed (a high-efficiency model).

A numerical assessment to select the optimal geometry of a specific cyclone separator of wheat flour processing

AbstractIn this study, the effect of the cyclone body height on the flow field within the specific cyclone and also on the performance parameters of the cyclone has been investigated. The five heights of the cyclone as various configurations were I = 600, II = 675, III = 750, IV = 825, and V = 900 mm. A pressure‐based solver was used and the turbulent Reynolds stress model was utilized to simulate the flow. Then, the Lagrangian discrete phase model was used to simulate the solid phase. As the height of the cyclone increases, the pressure drop decreases. Also, the best separation efficiency and the highest particle velocity value were achieved at a height of 750 mm. The maximum values of turbulence intensity, skin friction coefficient, and strain rate were obtained as negative components of cyclone performance at the cyclone body height of 900 mm. The height of 750 mm was recognized as the best height of the cyclone's body.Practical ApplicationsApplying numerical simulation in food processing is a novel method to minimize equipment construction and reach a high‐accuracy design. Computational fluid dynamics can provide an accurate and detailed flow analysis in the cyclone separators utilized in the flour processing plant. The dimensional analysis can help the researchers to achieve the optimum design and enhance the cyclone performance by reducing pressure drop and increasing separation efficiency. Also, the maintenance cost would be significantly reduced due to detecting the critical sections and strengthening them.

Numerical Investigation of Cyclone Separators: Physical Mechanisms and Theoretical Algorithms

AbstractGas‐particle aero‐type cyclones have revolutionized biochemical processes, engineering industries, and environmental pollution protection by effectively separating particles from gas. These devices rely on gravitational energy and centrifugal force to dissipate particle phase energy, but achieving optimal energy efficiency while minimizing pressure drop remains challenging. This has led to the development of various cyclone designs in commercial industries, each with unique energy efficiency characteristics. The intricate gas‐particle flow inside cyclones is a critical issue impacted by cyclone geometry, operating conditions, and media parameters. Advanced numerical simulations have been employed to understand this complex flow pattern better, offering researchers valuable insights into the mechanisms of different cyclone separators. This comprehensive review explores the available numerical methods in the literature on cyclones and their corresponding validations. Computational numerical modeling is a promising technique for predicting cyclone energy efficiency, gas‐particle behavior, and overall performance. This investigation delves into the progress and numerical forms of gas‐particle flow cyclones, examining how different parameters impact cyclone performance and flow patterns within the two‐phase flow. The future developments and challenges that may further promote the development of aero‐type cyclone separators, providing theory and engineering support for future cyclone designs, are also covered. As a result, it can confidently be reported that aero‐type cyclone separators remain a critical component in various industrial sectors, offering energy‐efficient solutions for mitigating environmental pollutants and gas‐particle separation systems. With continued development and research, these devices will undoubtedly shape the future of energy processes and engineering industries, ushering in a new era of sustainability and efficiency.

Influence of nose angle on performance of dense medium cyclones with volute inlet

Dense medium cyclones (DMCs) are widely used in coal mine sorting processes to improve the quality of coal products and reduce pollution. The conventional linear inlet DMCs has the problems of unstable flow field, high turbulence density and low separation efficiency. Based on these concerns, the volute inlet DMCs was proposed, however the nose angle as one of the most critical parameters has not yet been investigated in depth. In this paper, a DMC with volute inlet is investigated, and the effect of nose angle is studied by a computational fluid dynamics model in terms of flow field, particle motion and the forces acting on the particles. The performance of the DMC is evaluated with respect to the inlet nose angle. As the nose angle increases from 0 to 180 deg., the separation efficiency has a tendency to increase and then decrease with the inflection point founding when nose angle is 180 deg. Then the flow field, particle distribution and particle force are analyzed respectively. The results show that the symmetry and stability of the flow field can be significantly improved as nose angle increases from 0 to 180 deg., but they remain almost constant when nose angle is 270°. In addition, a quantification method of the short-circuiting flow is established and it has been found that increasing the nose angle can notably reduce the short-circuiting flow. In terms of particle phase, increasing the nose angle causes heavier particle distribution tends to concentrate. During this period, the variation pattern of forces on particles with different nose angles is also analyzed. The DMC with a nose angle of 180 deg. has a longer acceleration zone at the entrance height and an increased radial force on the particles, which results in better performance. This study provides a theoretical basis and reference for the structure optimization of dense medium cyclones.

Experimental investigation on flow splitting for the elimination of localized secondary flow in cyclones and enhancement of their performance

The limitation of cyclone performance is attributed to the presence of localized secondary flow, including longitudinal circulation, short circuit flow and eccentric circulation. The present study proposes an enhanced cyclone with split flow (ECSF) to effectively suppress the local secondary flow in cyclones. An experimental setup was constructed to evaluate the performance of ECSF under various operating conditions. The results of the experiment demonstrate that the separation efficiency of ECSF surpasses that of Lapple cyclone due to the synergistic effect of split flows in both the by-pass flow and underflow. When the feed velocity is 13 m/s, the ECSF exhibits a reduced separation efficiency of 89.8% for 10 μm silica particles, which surpasses that of the Lapple cyclone by 10.6%. The ECSF achieves its maximum total and reduced separation efficiencies at a feed velocity of 27 m/s, reaching values of 96.3% and 95.7%, respectively. Compared to the Lapple cyclone, the ECSF demonstrates an extended range of operational capabilities with respect to feed velocity. By maintaining a constant total split ratio in ECSF while increasing the proportion of by-pass flow, it is possible to improve its separation efficiency without augmenting overall energy consumption. The findings of this investigation offer valuable insights for enhancing the dust removal efficiency of cyclones.

Numerical investigation of filtering cyclones using response surface methodology and CFD simulation approaches

The cyclone separator pressure drop depends on the geometry and the operating conditions. Alternative equipment to decrease pressure drop is the filtering device. In this paper, the effect of inlet height, inlet flow rate, and conical section permeability about the filtering cyclone performance (Euler number) is studied through CFD simulations. The experimental and numerical results indicate that the turbulence model Large-Eddy Simulations (LES) reasonably predict the pressure drop in high swirling flows in filtering cyclones. CFD simulations suggest the Euler number increase with the increase of inlet height and decrease with the increase of flow rate and permeability. However, there is an interaction between the permeability with the other two variables. Therefore, this study suggests that CFD models can be used as instruments to evaluate same structural and operational variables in the filtering cyclone performance.

Study on the performance of downhole axial cyclone with spiral fins for drainage and sand removal

When dewatering and resurrecting natural gas-flooded wells, sand-out problems can pose a serious hazard to downhole tools. At present, the downhole cyclone has more research on the separation of large particles of 60–70 µm, which is a serious hazard, but there is little research on the separation of fine particles of 10 µm. To improve the separation efficiency of downhole fine sand particles, this paper designs a new type of axial cyclone, in which a spiral fin is installed at the axis of the cyclone to improve the strength of the cyclone inner cyclone flow through the spiral fin so that the fine particles involved in the inner cyclone flow are thrown back into the outer cyclone flow area. This paper combines theoretical analysis, experimental study, and numerical simulation to compare and analyze the fluid transport law and internal flow field characteristics in the new cyclone and the basic cyclone, and the results show that the separation efficiency of the new cyclone for 10 µm fine particles is significantly improved and the pressure drop is slightly increased. In this paper, we also optimized the structural parameters such as envelope diameter, pitch, and length of the spiral fins. The separation performance is optimal when the envelope diameter is 10 mm, pitch is 40 mm and length is 240 mm, and the separation efficiency of 10 µm fine particles can reach 65.1%, which is a year-on-year increase of 99.1% compared with the basic separator, and the pressure drop is 0.231 MPa, which is a year-on-year increase of 31.2%.

Analyzing the performance of cyclones and scrubbers as air pollution control methods for household solid waste incinerator

Household solid waste processing through incinerators may pose environmental problems, as gas emissions from combustion are released. Air Pollution Control Devices (APCD), such as cyclones and cyclone scrubbers, are frequently utilized to mitigate these issues. This study aims to evaluate the efficacy of cyclones and cyclone scrubbers as APCD for incinerators. To conduct the study, gas emissions for the parameters SO2, NOx, and CO were measured from the combustion of mixed waste in an incinerator with a fixed waste composition. Data were collected every 5 minutes within 45 minutes of combustion at the inlet and outlet of each APCD. The results indicate that using a cyclone can eliminate 37% of NOx and 91% of CO emissions. In contrast, a cyclone scrubber can remove 53% of NOx and 96% of CO emissions. Notably, the gas analyzer failed to recognize the SO2 parameter. Implementing a cyclone can reduce gas emissions from incinerator combustion, and combining a scrubber within the cyclone can increase its effectiveness in reducing these emissions.

Square Cyclone Separator: Performance Analysis Optimization and Operating Condition Variations Using CFD-DPM and Taguchi Method

The square cyclone separator is an efficient separation device for high-temperature gas within Circulating Fluidized Bed (CFB) boilers. Additionally, other operating factors such as particle loading and gas velocity are frequently thought to have considerable influence on fluid flow in gas cyclones, making parameter optimization essential. Finding the most suitable operating configuration can be challenging because of a fundamental understanding of the operating principles, which has yet to be taken into consideration in the literature. The gas flow inside a square cyclone was analyzed using Computational Fluid Dynamics (CFD) for investigating parameters including particle mass flow rate, inlet velocity, inlet temperature, and turbulent intensity in this research. The Taguchi method was utilized as a Design of Experiment (DoE) methodology to maximize separation efficiency. The Analysis of Variance (ANOVA) was conducted to evaluate the relative contribution of each parameter to the performance of the gas cyclone, while the Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations were solved using the Eulerian-Lagrangian approach to represent particle movement. Also, Discrete Random Walk (DRW) was incorporated to account for velocity fluctuation. According to a Taguchi analysis, particle mass flow rate is the parameter that has the least impact on cyclone performance, whereas inlet velocity has the most contribution. From the different range of factors examined here, it is proved that the optimal levels of factors for inlet velocity, inlet temperature, particle mass flow rate, and turbulent intensity are, respectively, 20 m/s, 300 K, 180 g/min, and 4%.

Geometry optimization of axial cyclone for high performance and low acoustic noise

Axial flow cyclones are widely used to separate gas-particle mixtures in many industrial applications. This study aims to optimize the axial cyclone pressure drop, removal rate, and sound levels. Single and multi-objective optimizations using a surrogate model were used to minimize the Euler number, Stokes number, and overall sound pressure level (OASPL). A radial basis function artificial neural network approach was also applied to generate more reliable data. The performed three single-objective genetic algorithms optimization studies led to the minimized Euler, Stokes, and OASPL numbers values of 5.082, 0.333, and 3.607, respectively. Then, the multi-objective NSGA-II optimization technique was used to generate a Pareto front that decision-makers can use for optimal performance. It was found that the concave guide vane, the guide vane revolution, and swirler geometry significantly affect the performance of axial cyclones. The low values of acoustic noise were recorded at low tangential and axial velocities values.

Influence of gas exhaust geometry on flow pattern, performance, and erosion rate of a gas cyclone

Influence of gas exhaust geometry on flow pattern, performance, and erosion rate of a gas cyclone