Cyclone Inlet Research Articles

CFD-DEM simulation of particle revolution and high-speed self-rotation in cyclones with different structural and operating parameters

Systematically researching the association of the turbulentflow in cyclone with the particle revolution and high-speed self-rotation may provide new insights for improving the separation performance and expanding the application of cyclones. In this study, the effect of cyclone structural parameters and inlet gas velocity on the continuous phase flow field as well as the revolution and high-speed self-rotation of the dispersed phase particles. It was observed that the particle self-rotation speed increases with the increase of cylinder-to-cone ratio, the decrease of the cone angle, and the increase of the inlet gas velocity. With the cylinder-to-cone ratio, i=1, half-cone angle, α=4.7° and the inlet gas velocity of 20 m/s, the average particle self-rotation speed was determined to be 7124 rad/s. Meanwhile, it was also revealed that the cyclone structure and inlet gas velocity remarkably affected the velocity of the flow field, vorticity, pressure drop and residence time of revolution movement of particles within the cyclone. This study can provide theoretical fundamental for the industrial applications of cyclone in chemical engineering and environmental engineering related to the separation of pollutants on the surface of particles and in pores.

Development of cutoff size adjustable omnidirectional inlet cyclone separator

The cyclone separator, which is commonly used for size classification and collection of aerosols, have sampling bias that depend on the installation direction of the inlet and significantly limit the change in cutoff size. In this study, these shortcomings were addressed in the developed cutoff size adjustable omnidirectional inlet (CSAOI) cyclone separator, which can suction aerosol from all 360° directions and allows the adjustment of cutoff size without the need to change cyclone geometry or operating flow rate. Although the aerosol was suctioned from the side in a similar way to conventional tangential inlet cyclone separators, an omnidirectional inlet was implemented by installing 16 guide vanes along the circumference of the cyclone separator. As changing the installation angle of the guide vanes also changes the gap between the neighboring guide vanes, the cutoff size can be adjusted because the inlet velocity of the inflow aerosol is changed by the gap under a fixed operating flow rate. A CSAOI cyclone separator was devised, fabricated, and tested for performance evaluation with an operating flow rate of 1,000 L/min. The cutoff size changed from 1.4 to 12.4 μm as the guide vane angle varied between 26° and 46°. For guide vane angles of 29°, 34°, and 42°, the cutoff sizes were 2.8, 5.4, and 10.0 μm, respectively, thereby confirming that the cyclone separator can be used as a PM2.5, PM5, or PM10 sampling inlet, respectively. The developed CSAOI cyclone separator is expected to be applied to various aerosol sampling and collection devices.

Substantiation of efficiency and ecological safety of technologies and cyclone plants of a new generation in iron ore dressing and processing

Methods of complex generalization, analysis and evaluation of practical experience and scientific achievements in the field of creation and introduction of new technologies and technical means for substantiation of efficiency and ecological safety of cyclone plants of a new generation, when dressing and processing iron ore, capable to improve environmental protection and working conditions, as well as to reduce the loss of useful product are described. It is established that dimensions of a permanent magnet depend on its properties and the distance of the plant`s working zone from the pole. For ferrobarium magnets and the distance of up to 3 mm, the width of the pole may not exceed 1 cm and the thickness – 42 mm; for the distance of 7 mm, the optimal width will be 2 cm and thickness – 70 mm. With that, for continuous regeneration of deposition surfaces, the optimal ratio of the pole pitch to the pole width is 2.44. It is proved that the efficiency of magnetic dust capture increases with increasing cyclone size and force acting on the particle, and decreases with increasing velocity in the cyclone inlet and the diameter of dust particles. In this case, the total inertial-magnetic efficiency does not depend on the cyclone size and averages 92%. The design of the cyclone plant for wet purification of air and gases is proposed, in which the plant poles pitch depends on the distance to the magnet pole, and the dependence of the magnetic force is always close to the exponent Fx = 1640exp (–0.268x), when the field induction for magnets on the pole surface is 0.1 T. The developed cyclone plant allows to catch any dust with efficiency more than 60% even at increase in speed of a stream in the inlet pipe by 1,5–2 times, and also to exclude air suctions and penetration of liquid drops in the cleared stream; reduce the loss of the useful product, return it to the technological process and reduce the dust load on the environment.

Computational and Experimental Analysis of Axial Flow Cyclone Used for Intake Air Filtration in Internal Combustion Engines

The properties and advantages of axial flow cyclones are presented; several dozen of them are already widely used as the first stage of inlet air filtration in internal combustion motor vehicle engines, work machines and helicopters. The necessity to conduct research on cyclones to improve separation efficiency has been demonstrated. Using the commercial engineering software Ansys Fluent, at a constant inlet velocity of 10 m/s, an assessment was made on the effect of the separation length and inlet diameter of the outlet tube on changes in separation efficiency in axial flow cyclone. Each of the examined parameters was variable while maintaining other factors at a constant level. In the numerical calculations, test dust was used, which was the equivalent of AC fine dust, the particle size composition of which was taken into account using the Rosin–Rammler model. Increase in the separation efficiency was observed with an increase in the separation length and a decrease in the diameter of the cyclone inlet tube. For the cyclone model with an increased separation length and reduced diameter of the inlet pipe, numerical tests of separation efficiency and pressure drop were performed for various velocities at cyclone inlet in the range of 2.5–15 m/s. The obtained characteristics of modified axial flow cyclone were experimentally verified on a laboratory stand during cyclone prototype tests, the model of which was printed using the additive manufacturing technique.

자동차 브레이크 미세입자 포집을 위한 소형 사이클론에 관한 연구

There has been an increasing interest in the collection of fine dust generated by vehicle brakes ever since the significant decrease in emissions from the exhaust system. Herein, we investigated the effective collection of brake fine dust by applying a mini-cyclone. Numerical analyses of steady and unsteady flows for a rotating disk were performed. When the disk rotation speed was 1000 rpm, the brake cooling air exited the cooling passage at approximately 20 m/s and air flow entered the cyclone inlet at approximately 7 m/s. At this inlet velocity, the vortex flow in the cyclone was well developed, thereby indicating the potential of efficient particle collection. Numerical analysis of transient particle flows for a mini-cyclone was performed to determine the particle collection efficiency. Results indicated that the particle collection efficiency exceeded 90% for particle diameters exceeding 3 μm. Therefore, the mini-cyclone can be effectively used for collecting brake fine dust.

Analysis of Bubble Flow Mechanism and Characteristics in Gas–Liquid Cyclone Separator

The separation of bubbles in a gas–liquid cyclone is complicated. A combination of numerical simulation and visual experimentation was considered apt to reveal the microscopic mechanisms of bubble flow. First of all, cyclones with different structures were numerically simulated. The calculation results show that the larger the diameter of the exhaust port, the better the bubble flow effect. When the exhaust port diameter was 24 mm, the gas discharge efficiency was 8% higher than that with an exhaust port diameter of 16 mm. The sequence of the bubble flow effect of a four-structure cyclone was obtained, and the gas discharge efficiency of the cyclone with a rectangular inlet was 7% higher than that of the trapezoidal inlet. Finally, a visual experimental platform was built to compare the rectangular inlet cyclone and spiral inlet cyclone with the best bubble flow effect. In accordance with the simulation numerical calculations, the bubble flow effect of the rectangular inlet cyclone was better than that of the spiral and trapezoid inlet cyclones, and the rectangular inlet in the middle was better. This article provides a specific theory and experience to guide further research on the separation mechanism, flow field characteristics and structurally optimal design of gas–liquid cyclones.

Experimental study of large-scale single and double inlet cyclone separators with two types of vortex finder

The effect of the two types vortex finder on the performance of the single and double inlet cyclone separators was experimentally investigated. In particular, the collection efficiency, pressure drop, and overall performance of single inlet cyclone separator with a cylindrical vortex finder, single inlet cyclone separator with an inverted-cone vortex finder, double inlet cyclone separator with a cylindrical vortex finder, and double inlet cyclone separator with an inverted-cone vortex finder were obtained and compared. The results show that the increasing diameter of the vortex finder would decrease the collection efficiency and pressure drop of the double inlet cyclone separators and increase the overall performance. It also found that inverted-cone vortex finder provides higher collection efficiency and pressure drop. Furthermore, when the vortex finder shape of the single inlet and double inlet cyclone separator changed, the variation of the collection efficiency and pressure drop was different, which is the same as changing the cyclone from a single inlet to double inlet.

Improving the energy efficiency of cyclone dust collectors

Our study, aimed at assessing the impact exerted by the inclusion to a low-efficiency cyclone of an additional "bypass" pipe connecting the cyclone's inlet branch pipe and the exhaust pipe, has been established the mechanisms to improve the energy efficiency and the process of purifying air from dust. It has been proven that the increase in the degree of purification is explained by a decrease in the radial flow rate under the exhaust pipe of the cyclone. The decrease in hydraulic resistance is due to a decrease in the flow rate along the inlet branch pipe when the air is fed separately to the body through the inlet branch pipe and the "bypass" pipe. Our experimental study has confirmed that when the cyclone design is supplemented with a "bypass" pipe in the most dangerous area of the cyclone in terms of dust release (under the exhaust pipe), the radial rate of the gas flow that negatively affects purification is reduced. This leads to an increase in the overall degree of purification from dust. The result of analytical calculations and computer simulation by the SolidWorks-2009 software were experimentally confirmed when investigating the effectiveness of dust capture from powdered skimmed milk in an industrial cyclone (a 630-mm diameter) with a "bypass" pipe. Such a cyclone is installed in the system of pneumatical transportation at the spray dryer "CT-500" at Ichnya Milk Powder and Butter Plant (Ukraine). Specifically, it has been established that the removal of dust is reduced almost twice, hydraulic resistance ‒ by 15 %, and the energy efficiency of the cyclone with a "bypass" pipe increases by 2.43 times.Thus, there is a reason to argue about the possibility of significant energy efficiency improvement of the cyclone with a "bypass" pipe.This makes it possible to assess the energy efficiency of the cyclone in the early stages of design

Development of a kinetic model for particles size reduction in cyclones

Attrition of particulate materials can bring unwanted effects, such as variation in the properties of solids as well as the generation of fines which may be emitted into the atmosphere. Therefore, it is important to know how the particle size varies when manipulating solids. In the present study, a model is proposed to account for the particle size variation in cyclones, considering five particle size classes. Experiments were conducted using FCC catalyst particles, flowing in a cyclone with different inlet velocity and load ratios. An Arrhenius type equation was used to generalize the regressed kinetic parameters for other operating conditions. Results indicate that the cyclone inlet velocity and solids load ratio affect significantly the particles size reduction in cyclones. The proposed model was able to predict the variation trends, which highlights its usefulness for the evaluation of FCC units, where the catalyst is recirculated several times through cyclones.

Fine generation ratio of iron ore in the cyclone of a gas–solid circulating fluidized bed

The generation of fines by attrition in fluidized bed reactors can cause problems. Thus, the objective of this study was to examine the amount of fines generated in the cyclone not only by attrition, but also by detachment of fine attached to surface according to time. Using a circulating fluidized bed (0.076 m ID × 3.7 m height), variables including cyclone inlet velocity (20.6–30.9 m/s), solid loading ratio (0.5–1 kg-solid/kg-air), and elapsed time (0.5–13 h) were investigated. The fine generation ratio was analyzed by dividing it into two components: the surface particle detachment ratio and the attrition ratio. The surface particle detachment ratio decreased rapidly with increasing cyclone inlet velocity and solid loading ratio. The attrition ratio was positively affected by the cyclone inlet velocity but negatively affected by the solid loading ratio, as found in previous studies. As the surface particle detachment ratio decreased with elapsed time, its contribution to the amount of fine particles generated decreased over time (73%–91% at 0.5 h and 41% at 5 h). The mass fraction produced by surface particle detachment was approximately 9% for the iron ore and 0.01% for catalyst particles.

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.

Numerical study of vortex eccentricity in a gas cyclone

This paper presents a numerical study of the vortex eccentricity in a gas cyclone and its effect on the performance of the cyclone. The gas flow in the cyclone was modeled as an unsteady flow by the Navier–Stokes equations with the Reynolds Stress Model (RSM) as the turbulence model. The particles were modelled by the Lagrangian particle tracking (LPT) approach in an unsteady gas flow. Gas cyclones with the same dimensions and total flow rates but different numbers of inlets were simulated with the inlet velocity varying from 12 to 20 m/s. The vortex eccentricities in different cases were analyzed in terms of radial deviation and angular deviation. In addition, the frequency of the precessing vortex core (PVC) was analyzed by the fast Fourier transform (FFT). The results show that the vortex center in the single inlet cyclone has a great eccentricity and its precession center is also different from the geometric center, which reduces the particle collection efficiency. The increase in the symmetry of the inlet causes only a very small increase in the pressure drop in the simulated cases, but it can significantly reduce the vortex eccentricity, particularly by eliminating the eccentricity of the PVC center. The improvement of the vortex eccentricity can generally increase the collection efficiency for particles greater than 2.0 µm. The increase of the collection efficiency is mainly because the symmetrical vortex can restrain the short-circuiting flow of particles. The results can improve the understanding of the vortex flow in gas cyclones which may guide the optimization of gas cyclones.

Simulation and Comparative performance analysis of Modified Cyclone Dust Separator

The cyclone separator is industrial equipment that is in use for a long time. Because of its industrial importance, a lot of extensive research work has been done. This paper discusses the efficiency of cyclones by considering the pressure loss and collection efficiency (cutoff diameter). The simulation of fluid-dust flow field in a cyclone is carried out using computational studies. The gas flow rate and temperature and geometrical parameters governing the efficiency of cyclone are the focus of this study. In this paper, the influence of the geometry on flow field pattern and performance of the tangential inlet cyclone separators are analyzed using computational work. The current work is carried out in three steps. First phase is dedicated to study the Stairmand’s optimized design to appreciate the pressure and speed fluctuations. This study if followed by examining the cyclone separator by varying the inlet width and height; and the cyclone total height. Finally, mathematical study to determine the efficiency of the dust separator is done.

DEVELOPMENT OF A CYCLONE SEPARATING UNIT ATTACHING TO LOCALTHRESHERS FOR CLEAN ENVIRONMENT

This study aims to obtain a clean environment through agricultural activities by developing and evaluating the performance of a cyclone separating unit attached to threshers. Threshing in traditional method depends on emitting chopped wheat straw (Tibn) off the threshers freely in the air and then collected manually by operators causing air pollution and affecting operators' health. The developed cyclone in this study separates dust from the airstream and simultaneously collect the chopped wheat straw instead of operators. According to the obtained data from theoretical calculations (Table 1), the modifications on 2D2D cyclone. The tested performance parameters of the developed cyclone are: four airstream velocities (ASV) of 2.3, 3.6, 4.7 and 5.5 m/s; cyclone inlet dimensions (CID) of (A) 20x30; (B) 25x35; (C) 35x45 cm for width and height, respectively; vortex finder length (VFL) of 50, 60 and 70 cm; cyclone outlets ratios (COR) chopped wheat straw and airstream outlet diameters of 15, 20, 25 and 20, 25, 30 cm for chopped wheat straw and airstream outlet represents ratios of 0.75, 0.80 and 0.83, respectively. The results were summarized in the following points: Separation and collection efficiency value by developed cyclone was 99.8% at inlet velocity of 4.7m/s, vortex finder length of 50 cm, with inlet dimensions of 25x35 cm under cyclone outlet ratio of 0.8. The maximum values of the rising dust was 6.8 mg/m3under the same mentioned conditions while increased by97.5 % with traditional method (without cyclone). Total costs for packing chopped wheat straw under mentioned conditions decreased by 80% in case of using the developed cyclone comparing to the traditional method. It is recommended to manufacture the developed cyclone with vortex finder length of 50 cm, with inlet dimensions of 25x35 cm at outlet ratio of 0.8 to lessen the environmental pollution and conserve laborers' health.

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

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

Optimization and experimental investigation in bottom inlet cyclone separator for performance analysis

The chemical engineering industries are utilizing the bottom inlet cyclone separator with venturi for separating the particles from an air/gas medium. For improving the performance of this equipment, important geometrical features such as venturi inlet width, total height of the cyclone and body height of the cyclone are considered for optimization. Central composite design was used in response surface methodology (RSM) to fit the regression equation. This regression equation was evaluated by analysis of variance (ANOVA). Then, this polynomial equation was optimized by particle swarm optimization (PSO) for minimizing the cut-off diameter. These optimized results were compared with genetic algorithm (GA) results. Based on this optimized result, an experimental setup was created for validation purpose. The experimental results were compared with GA and PSO results. A good agreement was obtained between these results. The magnesium particles were utilized for predicting the cut-off diameter of the new design. The Stokes number of this new design was less when compared with the mathematical model. The new design gives better performance when compared with the mathematical model. The numerical simulation was executed for predicting the particle collection efficiency, cut-off diameter and flow pattern inside the cyclone. The results were compared with the mathematical model and venturi inlet tangential entry cyclone.

Performance improvement of cyclone separator by integrated compact bends

The enhancement of particle separation is important for aerodynamic cyclones to reduce any extra or downstream capture process. To improve the particle separation performance, a new type of integrated compact-bend cyclone (ICBC) was proposed to achieve a non-homogeneous radial particle distribution at the cyclone inlet and hence reduce radial distance to the cyclone wall before performing the primary separation in the cyclone body. Experimental investigations and numerical simulation were performed to examine the enhancing effect of various integrated compact bends. The results proved the effectiveness of the integrated compact bends for improving particle separation performance. The grade efficiency for 1–5 μm particles was enhanced by up to 8.5% for 180° ICBC and 22.7% for 360° ICBC at 12 m/s inlet velocity, and by up to 8.0% for 180° ICBC and 20.5% for 360° ICBC at 20 m/s inlet velocity, respectively. Meanwhile, no significant difference in the gas flow pattern was observed for the different ICBCs. Furthermore, the results by computational fluid dynamics (CFD) simulation was demonstrated to reflect the enhancing effect of ICBs not included in other cyclonic separation theories. The result may provide a positive reference for cyclone-based intensified separation in the field of chemical and process engineering.

3-D Numerical Study of CFB 110 MW: Fluidization in Furnace and Cyclone with Loads And Air Combustion Variation

Circulating Fluidized Bed (CFB) Boiler has advantages when uses low rank coal compared to Pulverized Boiler. It will be less operational cost but it has greater risk in degradation because of sands material inside the process. Air combustion between primary air and secondary air is one importance parameter that influence fluidization of CFB. Numerical simulation of commercial CFD was used with Eulerian multiphase model implemented to analyzed sand volume of fraction, air and sand velocity including distribution of pressure around furnace. It was used 55%-45% air combustion ratio of primary and secondary air as reference when boiler operated at 63% and 100% based on operation performance of CFB and then it was simulated with additional variation of air combustion ratio with 50%-50%. Simulation of 110% load was added using all of variation of air combustion. The simulation showed that fluidization with air combustion ratio 50%-50% and 55%-45% executed well when operated at 63%. Meanwhile, fluidization 100% and 110% with all those air combustion ratios would cause a great number of sands entered inlet cyclone and higher sands and air velocities.

Studying the effect of vortex finder eccentricity on the gas cyclone performance

In this study, cyclone separator, with nine different vortex finder eccentricities are simulated computationally (CFD). The numerical technique is based upon solving three dimensional, incompressible, turbulent flow governing equations using the Reynolds stress turbulent model. The results show that moving the vortex finder eccentricities in two directions is more effective than moving it in one direction only. Case 5 achieves the lowest pressure drop where the vortex finder eccentricity is moved in the positive x and y directions toward the cyclone inlet. It is found that moving the eccentricities in both x, y directions towards the cyclone inlet reduces the pressure drops by 31% and decreases the collection efficiency by 17.4% compared to case 0 (where the vortex finder is concentric in the cyclone centerline).

Experimental and numerical study of Stairmand cyclone separators: a comparison of the results of small-scale and large-scale cyclones

Gas cyclone separators are employed to separate particles from gas. In this study, the effect of the vortex finder diameter, inlet velocity and particle size on the flow field and the performance of a large industrial Stairmand cyclone has been studied both experimentally and numerically. The vortex finder diameters used are 0.40, 0.45, 0.50 and 0.55 times the cyclone diameter. Cyclones with body diameters of 700 mm and 254 mm are used. Cyclone inlet velocity is changed from 11.5 m∙s−1 to 19 m∙s−1. Particle size is varied between 1 and 13 μm. Whether the correlations obtained for small-scale cyclones are valid for large-scale cyclones has been investigated. The three-dimensional numerical study is carried out by using ANSYS Fluent 17.0 software package for incompressible turbulent flow condition. Reynolds stress model is chosen as the turbulence model. Sawdust ash is used as particles. The results of numerical study are compared with the results of experimental study and literature. Results are found to be consistent with each other. It is seen that cyclone collection efficiency and pressure drop increase when both vortex finder diameter decreases and inlet velocity increases, but 50% cut-off diameter decreases. Results show that the correlations obtained for small sampling cyclones may not be appropriate for large-scale cyclones.