Cyclone Performance Research Articles

A Comprehensive CFD Assessment of Wheat Flow in Wheat Conveying Cyclone Validation and Performance Analysis by Experimental Data

Cyclone is often used in the Industry due to its low maintenance costs, simple design, and ease of operation. This work presents both experimental and simulation evaluation on the effect of inlet velocity and mass flow rate on the performance of a wheat conveying cyclone. According to the great importance of the pressure drop and separation efficiency on the separation phenomenon in the cyclone, a comprehensive study has been conducted in this regard. A computational fluid dynamics (CFD) simulation was realized using a Reynolds stress turbulence model, and particle-air interactions were modeled using a discrete phase model. The result showed a good agreement between the measured value and CFD simulation on the pressure drop and tangential velocity with a maximum deviation of 6.8%. It was found that the separation efficiency increased with inlet velocity up to 16 m s−1 but decreased slightly at a velocity of 20 m s−1. The pressure drop increased proportionally with inlet velocity. However, optimum performance with the highest separation efficiency (99%) and acceptable pressure drop (416 Pa) was achieved at the inlet velocity of 16 m s−1 and mass flow rate of 0.01 kg s−1.

A model for predicting the separation performance of a coupling cyclone with a built-in granular bed filter

A separator coupling cyclone with built-in granular bed filter was proposed for gas purification. By analyzing available data in published literature and experimental results, a new model for predicting the separation performance of the coupled separator was obtained by regressing against a broad range of parameter governing the dusts collection in the coupled separator. In particular, the mutual influences between the cyclone shell and the built-in granular bed filter on the separation process were denoted by introducing a new dimensionless structural parameter. Different from other coupled models, the proposed model can be adopted to describe the total collection efficiency and the fractional efficiency of the cyclone/ granular bed filter coupled separator.

Experimental Investigation of the Effects of Helical Roof on the Performance of Stairmand High Efficiency Cyclone

Cost-effectiveness of a standard and a modified Stairmand high-efficiency type cyclone was compared at various inlet gas velocities. The modified design was obtained by replacing the roof of the standard design with a helical roof. Experiments were conducted by both standard and helical roof designs at the same operating conditions. Results showed that helical roof leads to reduced pressure drop in cyclones while having a negative impact on particle collection efficiency. Reductions in pressure drop can reach up to 30%, while particle collection efficiency is reduced by up to 8% simultaneously. Overall, the treatment cost of a cyclone separator can be reduced by 14.1–20.8%. Results indicated that helical roof design cyclones can be used to reduce overall treatment cost by cyclone separators.

Effect of horizontal resolution on the simulation of tropical cyclones in the Chinese Academy of Sciences FGOALS-f3 climate system model

Abstract. The effects of horizontal resolution on the simulation of tropical cyclones were studied using the Chinese Academy of Sciences Flexible Global Ocean–Atmosphere–Land System Finite-Volume version 3 (FGOALS-f3) climate system model from the High-Resolution Model Intercomparison Project (HighResMIP) for the Coupled Model Intercomparison Project phase 6 (CMIP6). Both the low-resolution (about 100 km resolution) FGOALS-f3 model (FGOALS-f3-L) and the high-resolution (about 25 km resolution) FGOALS-f3 (FGOALS-f3-H) models were used to achieve the standard Tier 1 experiment required by HighResMIP. FGOALS-f3-L and FGOALS-f3-H have the same model parameterizations with the exactly the same parameters. The only differences between the two models are the horizontal resolution and the time step. The performance of FGOALS-f3-H and FGOALS-f3-L in simulating tropical cyclones was evaluated using observations. FGOALS-f3-H (25 km resolution) simulated more realistic distributions of the formation, movement and intensity of the climatology of tropical cyclones than FGOALS-f3-L at 100 km resolution. Although the number of tropical cyclones increased by about 50 % at the higher resolution and better matched the observed values in the peak month, both FGOALS-f3-L and FGOALS-f3-H appear to replicate the timing of the seasonal cycle of tropical cyclones. The simulated average and interannual variabilities of the number of tropical cyclones and the accumulated cyclone energy were both significantly improved from FGOALS-f3-L to FGOALS-f3-H over most of the ocean basins. The characteristics of tropical cyclones (e.g., the average lifetime, the wind–pressure relationship and the horizontal structure) were more realistic in the simulation using the high-resolution model. The possible physical linkage between the performance of the tropical cyclone simulation and the horizontal resolution were revealed by further analyses. The improvement in the response between the El Niño–Southern Oscillation and the number of tropical cyclones and the accumulated cyclone energy in FGOALS-f3 contributed to the realistic simulation of tropical cyclones. The genesis potential index and the vorticity, relative humidity, maximum potential intensity and the wind shear terms were used to diagnose the effects of resolution. We discuss the current insufficiencies and future directions of improvement for the simulation of tropical cyclones and the potential applications of the FGOALS-f3-H model in the subseasonal to seasonal prediction of tropical cyclones.

Analysis of the novel hybrid cyclone separators using large-eddy simulation

In this study, we propose novel hybrid square-circular cyclone variants that take advantage of both square and circular cyclones. A total of five cyclone models are analyzed – a square cyclone (baseline model), two cyclone separators having a cylindrical segment over the top with the square section in the remaining part, and the two cyclone models having square segment over the top with a cylindrical section in the lower part. The performance of hybrid cyclones is evaluated using numerical simulations. Apart from mean as well as fluctuating pressure and velocity field, we closely examine the vortex core in both square cyclone and proposed hybrid cyclone geometries. With the proposed hybrid cyclone geometries, it is possible to have a flow field with or without the vortex core – this is a unique way of making selection. Furthermore, the enhancement in performance of hybrid cyclones is significant compared to the baseline model.

Computational Study of Operating Parameters on Performance of Compound Hydrocyclone

The dynamics of hydro cyclones is complex, because it is a multiphase flow problem that involves interaction between a discrete phase and multiple continuum phases. The performance of hydro cyclones is evaluated by using Computational Fluid Dynamics (CFD), and it is characterized by the pressure drop, split water ratio, and particle collection efficiency. In this paper, a computational model to improve and evaluate hydro cyclone performance is proposed. Computational turbulence models (renormalization group (RNG) k-ε, Reynolds’s stress model (RSM), and large-eddy simulation (LES)) are implemented, and the accuracy of each for predicting the hydro cyclone behavior is assessed. Four hydro cyclone configurations were analyzed using the RSM model. By analyzing the streamlines resulting from those simulations, it was found that the formation of some vortices and saddle points affect the separation efficiency. Furthermore, the effects of inlet width, cone length, and vortex finder diameter were found to be significant. The cut-size diameter was decreased compared to the Hsieh experimental hydro cyclone. An increase in the pressure drops leads to high values of cut-size and classification sharpness. If the pressure drop increases to twice its original value, the cut-size and the sharpness of classification are reduced to their initial values, respectively.

Numerical investigation of separation efficiency of the cyclone with supercritical fluid–solid flow

The utilization of hydrogen is gaining increasing attention due to its high heating value and environmentally friendly combustion product. The supercritical water circulating fluidized bed reactor is a promising and potentially clean technology that can generate hydrogen from coal gasification. Cyclone is a vital part of the reactor which can separate incomplete decomposition of pulverized coal particles from mixed working fluid. This paper aims to gain in-depth understanding of the cyclone separation mechanisms under supercritical fluid by computational fluid dynamics (CFD). Although the amount of supercritical carbon dioxide in mixed working fluid is minor, it obviously influences the flow fields and separation efficiency of a cyclone. The simulation results suggest that both the decreasing content of supercritical carbon dioxide and adding the extra dipleg cause the promoting performance of cyclones. Research findings could refine the design of supercritical fluid–solid cyclones.

Cyclone pressure drop reduction and its effect on gas–particle separation capability: principle, performance, and assessment

Abstract Cyclone separators have been widely used for gas–particle separation in chemical engineering. However, their enhancement in separation performances usually increases the pressure drop, which inevitably leads to an increase in operating energy consumption. One of the challenging issues is how to reduce the cyclone pressure drop while improving separation performances. To gain insight into the pathways and impacts of cyclone pressure drop reduction, this work reviews the state-of-the-art technical principles, performances and effects, focusing on the processes, mechanisms, and characteristics of pressure drop reduction by inlet/outlet variations, additional auxiliary devices, local cyclone dimension improvement, and global optimization based on intelligent algorithms. The cyclone performances are assessed using a proposed index that combines the Euler number and the square-root particle cut-off Stokes number. It is suggested that the pressure drop and separation capability usually have a dynamic compromise. Considering the comprehensive performances, the technology using helical roof inlet, cross cone, increasing cylindrical height with h/D = 4.3 (H/D = 6.35), and globally optimized design by Sun et al. (2017) are respectively considered to the others. Particularly, the last one is recommended to be more representative in practice. Finally, the key issues to be considered in further research were also prospected.

An Overview of Numerical Simulations on Gas‐Solid Cyclone Separators with Tangential Inlet

AbstractCyclone separators play a dominating role in fluid catalytic cracking, biomass pyrolysis, dedusting, demisting, heavy oil regrading, etc. Separation mechanism, pressure drop, particle size, collection efficiency, gas underflow, gas inlet velocity, particle loading, cut‐off size of particles, and gas residence time are the main cyclone performance criteria. In the present work, the particle separation theory is explained and recent developments of numerical simulations of different cyclone separators with tangential inlet are summarized. Besides, the effect of different parameters on cyclone performance is discussed and several suggestions are provided based on previous numerical simulations.

Computational fluid dynamics study of the impact of surface roughness on cyclone performance and erosion

In this study, the effect of roughness of cyclone wall on the rate of erosion and cyclone performance was studied using the CFD technique with the aid of the Ansys-Fluent 19.2 software. The Reynolds stress transport model was used to simulate the airflow turbulence in the rotating flows in the cyclone. The validated computational model was used, and the variations of axial velocity, tangential velocity, collection efficiency, cyclone pressure drop, and rate of erosion for different wall roughness were evaluated. For simulating surface erosion, the Oka model was used. The result of this study revealed that the wall roughness significantly affected airflow behavior in the cyclone and the resulting cyclone performance. In addition, when the wall roughness increased, the wear rate decreased. It was also found that the solid loading and inlet gas velocity significantly affect the erosion rate and even more than that of particle size.

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.

Modelling and simulation of a Single Cyclone for Optimal Efficiency for a Batch-Type Fixed-Bed Down-Draft Gasifier using CFD

Modelling and optimization have long been established as a means of achieving efficiency in energy systems also in sustaining the environment. In Nigeria, where environmental pollution have become a challenge, the problem of pollution and safety has become a global concern whereby sustainable power generation systems with zero greenhouse emission will serve as a better way of sustaining the environment. Simulation been a basic similitude tool to real life engineering design enable the engineers to understand the interactive flow process within an operating systems, postulating operation results, designing process systems or optimizing the operating system with optimum accuracy. This tool enables an engineer to establish the geometrical parameters for the actual design of the system. Cyclones, which are widely used as air pollution abatement equipment, are used in processing industries for removal of particulate matter (PM). A 1D2D centrifugal fan power driven cyclone is attached to a batch-type fixed-bed downdraft gasifier was modelled and simulated to determine the behaviour of the gasification products and the optimal efficiency of the cyclone. Applying mathematical modeling and CFD tools to understand the effect of the gas stream on the cyclone performance and a new optimized cyclone geometrical ratios based on the mathematical model was attained. Establishing the cyclone modelling was done by applying the heat content simulation tool (MATLAB-Software package) and using the response surface methodology (RSM) approach. The geometrical parameters in cyclone separators significantly affected the flow field and performance parameters. Analysis of the experimental design informed the researcher on the relationship between the effects of inlet dimensions and the vortex finder diameter on the performance of the cyclone. The cyclone design and simulation of the cyclone has shown that it can effectively remove solid particles from a gas stream (syn-gas). The calculation shows that collection efficiency for particle size of 13.18 μ m is obtained for the cyclone separator assuming all the particles leaving the cyclone is at that size. The designed simulated cyclone show that the new design when compared with the Stairmand design have a better performance over the later.

Performance evaluation of standard cyclone separators by using CFD–DEM simulation with realistic bio-particulate matter

As an abatement emissions control and energy-consuming device, cyclone separators are the most common device used in bioprocessing to separate fine and coarse particulate matter (PM) from the gas flow. In this investigation, four standard cyclones geometries viz. 1D2D, 2D2D, 1D3D, and 1D3D with 2D2D inlet (1D3D/w2D2D) in addition to a designed one, were simulated to investigate the performance characteristics. The D's refers to the cyclone diameter, and the numbers before each D's relate to the length of the cylindrical and conical sections, respectively. The PM used for testing and modeling was conducted on two types of real heterogeneous bioparticles (jojoba seeds and their leaves). This research is considered the first head start approach to predict the cyclone performance under the true shape modeling of PM. Discrete Element Method (DEM) was employed to simulate the trajectory of each particle, taking into consideration the interactions and collisions. Simultaneously, the Computational Fluid Dynamics (CFD) was used to simulate the highly curved streamlines and the chaotic turbulence of the continuum airflow with the Reynolds stress turbulence model (RSM). The designed cyclone was used to validate the results, which showed a good agreement between simulated data and the experimental work. The result showed that the 1D2D cyclone design has a better performance than that of the other cyclones. The methods used in this work for analyzing the phenomena occurring inside the cyclone separator allow for the conclusion that cyclone performance not only varies significantly with the cyclone type but the operating conditions as well. With these presented characteristics and evaluations, industrialists can utilize the mentioned designs for different processing to get high performance using a coarse and large PM process.

Experimental and numerical studies on a new double-stage tandem nesting cyclone

This paper proposes a new type of gas cyclone separator, which nests an inner cyclone with a double-spiral inlet in an outer cyclone. Experiments were conducted to compare the separation performance of the new cyclone to that of the traditional Lapple cyclone. In addition, the flow fields and the particle collection in the two cyclones were simulated by the computational fluid dynamics (CFD) and compared. Compared with the traditional Lapple cyclone, the new double cyclone can present significantly improved collection efficiency, resulting from the two-stage separation and better symmetry of the flow field. On the other hand, the pressure drop of the new cyclone was only slightly elevated because of the low velocity in the outer cyclone. Moreover, this new double-stage cyclone separator can be further developed for particle classification, as the particles collected in the three outlets of the cyclone are in different size ranges.

Performance evaluation of industrial large-scale cyclone separator with novel vortex finder

This paper presents an experimental and numerical study on an industrial large-scale tangential-inlet cyclone separator with a novel and easy-to-implement vortex finder. The vortex finder was designed with slots on the side wall to improve cyclone performance. The collection efficiency, pressure drop, and interior flow field were analyzed. The proposed device provides an effective gas flow pathway and a coupled swirl-inertia separation mechanism, which eliminates short circuit flows under the bottom inlet of the slotted vortex finder to reduce the swirling intensity and minimize the flow instability in the separator. The pressure drop was reduced up to 27.9% compared to the conventional separator and the maximal increase in collection efficiency was 5.45%. The results presented here may provide a workable reference regarding the effects of vortex finders on improving flow fields and corresponding performance in industrial large-scale cyclone separators.

Influence of the inlet cross-sectional shape on the performance of a multi-inlet gas cyclone

The influence of inlet cross-sectional shape on the flow pattern, pressure drop, and cut-off diameter of a gas cyclone was studied using the CFD model. Accordingly, five different inlet cross-sectional shapes, namely, circle, ellipse, rectangle, square, and trapezoid, for the double-inlet gas cyclone were studied. It was observed that the maximum tangential velocity was about 1.95 times the corresponding inlet velocity for primary and secondary rectangle inlets. Furthermore, the computed tangential velocity in the cyclone with the primary and secondary rectangle inlets (R-R) was considerably greater than those obtained by the other inlet shapes. In this case, the axial gas velocity reached its highest values at the bottom of the vortex finder and the cyclone center. It was also determined that the inlet shape significantly affected the cyclone pressure drop. The Circle-Square and the Rectangle-Ellipse configurations of inlet cross-sectional shape generated, respectively, the lowest pressure drop and the highest efficiency.

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.

True shape modeling of bio-particulate matter flow in an aero-cyclone separator using CFD–DEM simulation

The multi-phase flow of air and bio-particulate matter exists in many biological and environmental systems such as aerodynamic separating devices, fluidized bed combustion, and feed processing machinery. Integration of the computational fluid dynamics (CFD) and discrete element method (DEM) codes was performed to study bio-particle loading ratios' effect on the cyclone device performance. Every individual particle's behavior was captured by a DEM model using Newton’s equations of motion, in which CFD modeled the continuum airflow for every computational cell scale through the Navier–Stokes equation. According to the high turbulence and chaotic behavior of the continuum airflow inside the cyclone separator, Reynolds stress turbulence model (RSM) was used. The particles used for testing and modeling were conducted on two mixture types of real-heterogeneous particulate matter, namely jojoba seeds and jojoba leaves, without any fly ash. The particles were geometrically modeled using their actual dimensions and shapes, considered the first head start research approach in the cyclonic separation and purification field. The influence of the interacting particle–particle and particle–boundary forces was taken into consideration. The numerical simulation results successfully predicted the cyclone performance at the designed conditions, which showed the best experimental data trend. These data are useful in future studies to modify the cyclone design and optimize bio-systems' operating conditions for separating the macroscopic particulate matter.

A CFD investigation into the enhancement of down-hole de-oiling hydro cyclone performance

Recently, hydro cyclones have gained a proper reputation in separating multiple phases and considering their versatile performance and valuable features, they are being utilized in plethora of industrial fields including pharmaceutical, chemical, mineral, and petroleum. Of their useful aspects, maintenance-free operation, high durability under severe temperature and intensive pressure, and high separation efficiency can be mentioned. Despite being widely utilized, there are some obstacles that hinders achieving the apex of hydro cyclones’ applicability. Among all the problematic issues, the presence of gas core in de-oiling hydro cyclones, which is formed due to the high turbulent conditions, is of significant concerns. In this article, there has been an attempt to investigate the effects of implementing rods with two different designs, on the performance of de-oiling hydro cyclones to either resolve and improve the abovementioned issues. The results of laboratory model regeneration, demonstrated reasonable agreement with experimental data; in fact, the highest error associated with the regenerated model was discerned to be 14 percent. The outcomes of proposed models authenticated noticeable augmentation in overall functionally of hydro cyclone, flow behavior enhancement, as well as separation efficiency improvement in comparison to the reference model. As such, the required time for the proposed models to meet the stable condition was enhanced about over 90 percent, and the separation efficiency for the oil particle diameter of 17 μm (as the best case) was enriched up to 34.75 and 26.83 percent for model A and model B, in comparison to the regenerated hydro cyclone model.

Numerical and Experimental Analysis of Flow Pattern, Pressure Drop and Collection Efficiency in a Cyclone with a Square Inlet and Different Dimensions of a Vortex Finder

The paper presents results of numerical simulations and experimental investigations of a cyclone with a square inlet and different dimensions of a vortex finder. Investigations were conducted for five, different cyclone models. The main goal of the research was to determine the influence of cyclone vortex finder geometry (diameter, length) on key parameters for a cyclone operation, such as: gas flow pattern, gas velocity and pressure distribution, pressure drop and collection efficiency. The analysis of flow pattern inside the cyclone was carried out with the use of CFD (Computational Fluid Dynamics) simulations, verified using CTA (Constant Temperature Anemometry). Similarly, pressure distributions, pressure drop and collection efficiency for cyclones were determined numerically and with measurements. The study demonstrated that dimensions of the vortex finder have a significant effect on a cyclone performance. The numerical visualisations of flow showed some unfavorable and beneficial effects and phenomena that may occur in cyclones. Moreover, the smallest pressure drop (305 Pa) was predicted for the cyclone with a maximum diameter of the vortex finder (De = 0.105 m), the largest (358 Pa) when this diameter was the smallest (De = 0.075 m). The tests did not show any significant influence of the vortex finder length on the pressure drop in a cyclone. A different tendency was observed in the case of collection efficiency. The maximum value of this parameter (89.5%) was predicted for the cyclone with the shortest vortex finder (s = 0.060 m), minimum (85.5%) when the vortex finder was the longest (s = 0.220 m). In this case, however, tests did not show a significant impact of an outlet diameter on the collection efficiency. Results and conclusions presented in this paper can be practically used for design optimization of cyclone separators, and also to select their operating parameters.