Cyclone Inlet 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.

Investigating Dual Inlet Cyclone Separator Performance: Effects of Vortex Finder Diameter, Shape, and Particle Diameter on Separation Efficiency and Pressure Drop

The diameter and shape of the vortex finder of cyclone separator plays a significant role in separation efficiency and pressure drop. Currently, there have been many studies conducted on the shape and ratio of vortex finder of cyclone separator. This paper aims to compare numerical results of Raynold stress turbulence model RSM with K-ε RNG numerical analysis results and analyse the effect of further variation of the vortex finder diameter and shape of dual inlet cyclone separators. Five variation of vortex finder diameters namely 291mm, 310mm, 330mm, 348mm, and 366mm, four types of vortex finder shapes namely normal (cylindrical), spiral, divergent and spiral-divergent have been studied with different particle diameter and constant inlet velocity. The result obtained from this study suggests that increasing the vortex finder diameter have negative effect on separation efficiency. It also shows that increasing the vortex finder diameter consistently decrease the pressure drop. From the result, it is been found that the 291mm vortex finder has higher separation efficiency than the rest. Analysis with different vortex shapes, the spiral-divergent shape proved to be best in terms of separation efficiency.

Experimental study on gas uniformity at the inlets of six cyclones in a CFB with multi-tracer gas method

To investigate the non-uniform distribution of different gases passing through the parallel cyclones, experiments were conducted on a circulating fluidized bed (CFB) equipped with six asymmetrical cyclones. A multi-tracer gas method was used, with CO, O2, and CO2 chosen to represent gases with different properties in the flue gas at the inlets of the cyclones. The uniformity of multi-gas distribution was evaluated by measuring the concentration deviations of each tracer gas passing through individual cyclones. The results indicate that the concentrations of multi-tracer gases are higher in the middle cyclone among the three, which are located on the tracer gas injection side during the test of single-side secondary air (SA) tracing. The maximum concentration deviation of tracer gases is for CO2, while the minimum is for CO. At the three cyclone inlets on the opposite side, the tracer gas with higher density exhibits a more uniform distribution, and the gas uniformity decreases as the density decreases. The effects of superficial velocity, SA ratio, bed inventory, and tracer gas injection region on the uniformity of gas distribution were studied. The results show that superficial velocity and SA ratio primarily affect the uniformity of higher density gases, while bed inventory has a greater influence on lower density gases. The gas distributions are most non-uniform, especially for CO2, when the tracer gas injection region is near the rear wall closer to the induced draft fan during the test of regional SA tracing.

Performance experiments and pressure drop prediction modelling of an energy-saving cyclone separator

The study proposes a new type of axial-inlet cyclone separator with the smaller cylinder-cone ratio and an expansion tube at the particle exhaust, named energy-saving cyclone separator, which offers several advantages over the traditional tangential inlet cyclone in engineering units. Experimental results demonstrate that the separation efficiency exceeds 83 % for fine particles smaller than 10μm, while the pressure drop is significantly lower than that of the commonly used PV-type tangential inlet cyclone separator, at only 44 % of the PV cyclone separator’s pressure drop. Moreover, the flow fields of energy-saving cyclone separator are measured to analyze its characteristics. It is found that the lower tangential momentum ratio in both the inner and outer swirl zones of energy-saving cyclone separator reduces the dissipation of dynamic swirl pressure at the bottom of the cone section and outlet pipe, resulting in a lower pressure drop. The high proportion of downward axial momentum in the outer swirl section causes the separated large particles to discharge through the dust exhaust, improving the separation efficiency of coarse particles. Furthermore, a model to predict the pressure drop of energy-saving cyclone separator is developed.

Performance Evaluation of Square Cyclone Separator with Cone Geometry Variations

Rapid industrial development with intensive operations increases exhaust emissions that are polluting the environment and human health. Efforts to overcome the problem are urgent to be realized, one of which is by using a particle separator such as a cyclone separator. Along with that, the design of a cyclone separator with the best performance is very important. Therefore, it is necessary to innovate and analyze the design of the cyclone separator by varying the cone geometry of the cyclone. This study aimed to determine the best square cyclone separator among square cyclone separators with various cone geometries, including single cone, dual inverse cone 1, and dual inverse cone 2. It was conducted by Computational Fluid Dynamics (CFD) simulation and experiments and then continued by comparing pre-determined aspects comprising pressure drop, collection efficiency, static pressure contours, tangential velocity contours in the cyclone body, tangential velocity vectors in the cone geometry, and tangential velocity vectors at the cyclone inlet. The single cone is the best among all cone variations since it fulfils more aspects better than the dual inverse cones, namely: dominantly lowest pressure drop of 188.5 Pa, static pressure contour of 10.42 Pa, tangential velocity contour of 3.06 m/s, flow direction of the tangential velocity vector in the cyclone geometry was at the centre of the bin, and flow direction of the tangential velocity vector at the cyclone inlet was parallel.

Particle high-speed self-rotation in cyclones with different diameters and application in catalyst deoiling

One of the keys of cleaner production in the petrochemical industry is the reduction and recycling of spent catalysts. The centrifugal force generated by the high-speed self-rotation of particles in cyclone provides a possibility for the recovery of oil in the porous catalyst. In this study, five cyclones with nominal diameters of 75, 150, 200, 300 and 500 mm were designed from the perspective of industrial scaled-up applications. The effects of structural and operational parameters such as cyclone diameter, particle diameter, and inlet flow rates on the particle self-rotation, revolution, temperature variation and residence time were investigated through CFD-DEM simulation and high-speed motion analyzer (HSMA). The results show that with the increase of the cyclone diameter, the particle self-rotation velocity gradually increases and the residence time becomes longer. For a 200 mm diameter cyclone, the smaller the particle diameter and the greater the inlet flow rates, the higher the particle self-rotation velocity, and the self-rotation velocity of 1 mm particles reached a maximum of 8000 rad/s. Particle high-speed self-rotation in cyclones was applied to spent catalyst deoiling at room temperature and pressure, and the deoiling efficiency with different operating parameters was investigated. This study can provide guidance for the self-rotation separation of pore contaminants in porous media.

Numerical study of the effect of axial cyclone inlet velocity and geometrical parameters on separation efficiency and pressure drop

The effects of cyclone separation length lm, outlet pipe inner diameter dw and swirl guide angle β were numerically studied for different inlet velocities: 2.5 m/s, 5 m/s, 7.5 m/s, 10 m/s in four cyclone models, using Ansys Fluent software. The fractional composition of the test dust was considered using the Rosin- Rammler model. Four cyclone models were tested for velocities in the range of 2.5–10 m/s and five particle size ranges. The mass proportion of particles in the cyclone and the filtration efficiency were determined, which is a novel method for evaluating cyclones. The lowest filtration efficiency, regardless of the cyclone model, was found, for particles in the 0–5 μm range, and the highest in the 20–40 μm range. Better results were obtained for higher values of lm smaller dw and β = 90o. Optimal performance and the highest value of the filtration quality factor is obtained by cyclone model B for υ0 = 5–10 m/s.

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.

Effect of number of inlets on performance and flow field of large‐scale cyclone separators

AbstractThe performance and flow field of large‐scale cyclones with different inlet numbers were investigated by using computational fluid dynamics methods. The results show that the efficiency, pressure drop, and performance factor of cyclones increase with the increase in the number of inlets, and the quadruple inlet cyclone having the best overall performance is supposed to adopt. The number of inlets of the cyclone increases, the tangential velocity increases, and the short‐circuit flow rate decreases; however, when the number of inlets is greater than 2, both variations are lessened. In this study, the vortex eccentricity of the quadruple inlet cyclone is the smallest, the vortex eccentricity of the double and triple inlet cyclone is comparable, and the vortex eccentricity of the single inlet cyclone is the most significant.

Experimental Analysis of Dual Inlet Cyclone Separator

Cyclone separators are suitable to remove particles in extreme conditions with high pressure and temperature during the gas-solid separation process. The important performance of cyclone separators is determined by the separation efficiency and pressure drop. The inlet parameters including the number of inlets, inlet geometry and inlet gas velocity affects the performance of cyclone separators. In this paper, the experimental investigation has been conducted to determine the effects of dual inlet to the separation efficiency of cyclone separators. The cyclone separator was fabricated using the acrylic materials to accommodate the flow observation and trajectories inside the chamber. The experiments were conducted at 9, 11 and 13 m/s of inlet velocity using three particle sizes at 277.5, 42.5 and 625 um. Results showed that as the particle sizes increases, the separation efficiency also increases up to 94.5% for 625 um particles. The findings indicate that the dual inlet cyclone separators increases the performance of cyclone separators especially to remove fly ash in the biomass processing plant and other gas-solid process.

Effect of inlet volute wrap angle on the flow field and performance of double inlet gas cyclones

In response to the divergent understanding of double inlet cyclone performance in the literature, the effect of inlet volute wrap angle on the performance and flow field of double inlet cyclone separator was studied by Computational Fluid Dynamic (CFD) method. The results showed that the inlet volute wrap angle can affect the comparison results of the single and double inlet gas cyclones with the same total inlet cross-sectional area and velocity. 0° and 90° volute double inlet improved the efficiency mainly by separating particles below 10 μm, while 180° volute double inlet had no separation advantage for any particles, so the symmetrical double inlet does not always improve the efficiency, and the appropriate inlet volute wrap angle should be selected according to the actual situation, otherwise, the expected performance requirements of the symmetrical double inlet cyclone cannot be achieved. Compared with the flow field, it is found that the inlet volute wrap angle changed the tangential velocity of the symmetrical double inlet cyclone separator, thus changing the performance.

Performance of an axial inlet cyclone separator and the programming design of guide vanes

In order to build a more stable flow field structure in the traditional axial flow vane-guide cyclone separator, a new type of cyclone is designed by inserting an expanding section between the cylinder and the particle exit tube. Experimental results show that the separator has a separation efficiency of over 80 percent for fine particles which average diameter is below 10 μm. For the design of this type of axial inlet cyclone, the structure of guide vane plays an important role. However, the calculation of guide vanes is a complex wok in the manufacturing process. In order to provide convenience for the design of different types of guide vanes, computer programming language (Python) is used in this study to calculate the key guide vane parameters automatically. By this way, relevant guide vane parameters can be quickly output after typing the design requirements. So that the complicated mathematical work is effectively simplified, providing great help in the design for scientific research or industrial manufacturing.

ИЗУЧЕНИЕ ВЛИЯНИЯ СКОРОСТИ ВХОДЯЩЕГО ПОТОКА НА ЭФФЕКТИВНОСТЬ ЦИКЛОНОВ

A study into the influence of the speed of the incoming dust flow and a size of the inlet of a cyclone on its performance. The structure of the flow field has been investigated by calculations made using the Reynolds Stress Turbulence Model (MTNR) for a cyclone separator. The findings show that the maximum tangential velocity in the cyclone decreases when the entry size to the cyclone increases. No acceleration occurs within the cyclone body (maximum tangential velocity is almost constant throughout the cyclone). Increased size of the cyclone inlet reduces the drop of pressure. The cyclone's cutoff diameter increases with the cyclone's inlet size (therefore, the overall efficiency of the cyclone decreases due to a low vortex strength). The effect of altering the entry’s width is more significant than its height, especially for the cut-off diameter. The influence of simulations of velocity fluctuation on prediction of collection efficiency of cyclone separators has been numerically investigated using MTNR and large eddy simulation (MBV). The Euler-Lagrange modeling approach was used by Solidworks Flow Simulation to simulate 3D non-stationary turbulent gas and solid flows in the high-efficiency Starmand cyclone. The simulation results have been compared with available reference data. An analysis of the findings shows that the MTNR and MBV could adequately predict the mean flow field. The study shows that the (MBV) performs well in predicting fluctuating flow field and capture efficiency for each particle size. The results show that prediction of collection efficiency, especially for fine particles, is greatly influenced by simulation of velocity fluctuations in cyclones.

The effect of axial cyclone inlet velocity and geometrical dimensions on the flow pattern, performance, and acoustic noise

This article studied the effect of the inlet velocity and various geometric dimensions on the flow pattern, collection efficiency, pressure drop, and acoustic noise of axial cyclones using computational fluid dynamics (CFD). The maximum values of tangential and axial velocity over inlet velocity were obtained for a guide vane revolution of 0.4 and a ratio of the swirler core diameter to the cyclone diameter of 0.3. It was found that the revolution of guide vanes also significantly affected the collection efficiency. In addition, the minimum values of the cut-off Stokes number, Euler number, and the overall sound pressure level (OASPL) were found to be 4.83 × 10−3, 4.014, 22.81 dB, respectively, while the minimal acoustic noise was observed for the guide vanes leading-edge exponent of 1.5. However, an increase in the Reynolds number did not alter the shape of the pressure and velocity contours but affected their magnitudes in the cyclone.

Experimental Investigation of Possibilities to Improve Filtration Efficiency of Tangential Inlet Return Cyclones by Modification of Their Design

It has been shown that tangential inlet return cyclones are commonly used for inlet air filtration of off-road vehicle engines. The wear of the engine elements, and thus their durability, is determined by the efficiency and accuracy of the inlet air filtration. It has been shown that the possibilities of increasing the separation efficiency or decreasing the pressure drop of a cyclone by changing the main dimensions of the cyclone are limited, because any arbitrary change in one of the dimensions of an already operating cyclone may cause the opposite effect. A literature analysis of the possibility of increasing the filtration efficiency of cyclones by modifying the design of selected cyclone components was conducted. In this paper, three modifications of the cyclone design with a tangential inlet of the inlet air filter of a military tracked vehicle were proposed and performed. The symmetrical inlet of the cyclone was replaced with an asymmetrical inlet. The cylindrical outlet tube was replaced with a conical tube, and the edges of the inlet opening were given an additional streamlined shape. The modification process was carried out on three specimens of the reversible cyclone with a tangential inlet. After each modification, an experimental evaluation of the modifications was carried out. The influence of the modifications on the cyclone’s efficiency characteristics and pressure drop was examined. Subsequent modifications of the cyclone were performed on the same specimen without removing the previous modifications. Tests were performed in the air flow range QG = 5–30 m3/h. Polydisperse “fine” test dust with grain size dpmax = 80 µm was used for testing. The dust concentration at the cyclone inlet was set at 1 g/m2. The performed modifications caused a slight (about 1%) increase in separation efficiency in the range of small (up to QG = 22 m3/h) flux values and about 30% decrease in pressure drop in the whole range of the QG flux, which positively influences the increase in engine filling and its power. There was a noticeable increase in filtration accuracy in the range of low and high values of QG flux, which results in a decrease in the wear of engine components, especially the piston-piston ring-cylinder (P-PR-C) association, and an increase in their durability.

An experimental and modelling study of the Selective Non-Catalytic Reduction (SNCR) of NOx and NH3 in a cyclone reactor

The Selective Non-Catalytic Reduction process was investigated through experiments and modelling in a bench scale cyclone reactor. Outlet and internal profiles of NO and NH3 concentrations were measured at varying operating conditions. Cyclone inlet temperatures between 866 and 1023 °C were used, while the inlet NO concentration was kept at ~500 ppm. Gaseous ammonia was injected in the cyclone inlet, with nitrogen carrier gas. 60–69% NO reduction was achieved at inlet temperatures of 975–982 °C, and stoichiometric ratio NH3/NO β≈1.6, with no ammonia slip. The main reaction zone was the inlet and upper cyclone chamber. The experiments was modelled using simple and detailed kinetics combined with simple reactor models and a compartment model suggested in this work. The qualitative trends of NO reduction and ammonia slip were predicted by the models. However, the ammonia slip was significantly over-predicted in most cases. The outlet concentrations were insensitive to choice of reactor model, while sensitive to temperature and kinetics. The compartment model quantitatively reproduced the cyclones NO concentration profiles, through its simplified representation of the cyclone flow and temperature gradients, while the NH3 profiles were only qualitatively predicted. The choice of bypass fractions showed a large influence on the ammonia profiles.

Effect of inlet area on the performance of a two-stage cyclone separator

The cyclone separator is an important separation device. This paper presents a new type of embedded two-stage cyclone, which includes a 2nd-stage cyclone (internal traditional cyclone) with multiple inlets and a 1st-stage cyclone (outer cylinder) that unifies the 2nd-stage cyclone inlets into one inlet. The Taguchi experimental method was used to study the two-stage cyclone separator's inlet area on its performance. Studies have shown that the increase of the 1st-stage cyclone inlet area and the increase in the number of 2nd-stage cyclone inlets (N) positively affect reducing the pressure drop and a negative effect on efficiency. It is recommended to use 2S (the original 1st-stage cyclone inlet area) of the 1st-stage cyclone inlet area and 2N of the 2nd-stage cyclone inlets when separating fine particles. Compared with a traditional cyclone, the pressure drop is reduced by 1303 Pa, the mass separation efficiency (Eq) is increased by 0.56%, and the number separation efficiency (En) is increased by 2.05%. When separating larger particles, it is recommended to use 2S of the 1st-stage cyclone inlet area and 4N of the 2nd-stage cyclone inlets. Compared with a traditional cyclone, although En decreases slightly, the pressure drop is reduced by 3055 Pa, and the Eq is increased by 0.56%. The research results provide new insight into the design of the cyclone.

Effect of inlet periodic velocity on the performance of standard cyclone separators

In some engineering applications, the inlet velocity of cyclones for gas-solid separation varies periodically with time. This investigation is based on a push chain concrete spraying machine, measures and trigonometrically characterises the inlet periodic air velocity. Four standard cyclones and a design cyclone have been simulated to investigate performance under inlet periodic velocity. The simulation of the particle and fluid phases of the cyclone was carried out using the Reynolds Stress Model (RSM) using Computational Fluid Dynamics (CFD). The designed cyclone was used to verify the simulation results, the simulation and experimental data were in good agreement. The results of the study show that the 1D3D/w cyclone is optimal for the gas-solid separation of push chain concrete spraying machine. The effect of cyclone inlet size on separation performance under periodic velocity is significant. Furthermore, the concept of hysteresis time is defined by the difference between the time corresponding to the peak number of escaped particles and the time corresponding to the inlet velocity peak. Inlet periodic velocity can lead to situations where particles enter the cyclone and then return to the inlet duct or even escape by the inlet.

A brief review on improving materials particulates using cyclone separator by geometrical and turbulence factors

A detailed literature review for the particulate materials collection efficiency and flow pattern for the dust collector/cyclone separator identifies significant use in the cement industry. The increasing air pollution in the industries is to be reduced by some means of restrictions and some engineering aid like pollution controlling equipment. The cyclone separator in the industries are ultimately used to separate the particulate materials from contaminated gas (i.e., cement kilns). Cyclone separators are used for gas solid and gas liquid separation, but this review details about separation of the gas solid from the cement kilns. The results from various reviews and critics reveal that increasing the circumferential length of the vortex finder lowers the collection efficiency and increases the overall performance of the twin inlet cyclone separators. It was also discovered that using an inverted-cone vortex finder improves collection efficiency and reduces pressure loss. A particulate size from the kilns can be larger than 2.5 μm and ranges up to 10 μm. The changes made in geometrical features and flow pattern improves the overall particulate materials collection performance of dust collecting setup.

High-volume sampler for size-selective sampling of bioaerosols including viruses

Owing to the recent global spread of the new coronavirus SARS-CoV-2, the development of technology to effectively detect viruses in crowded public places is urgently needed. In this study, a three-stage high-volume bioaerosol sampler was developed for the size-selective sampling of bioaerosols through the suction of air at a high flow rate of 1000 L/min. In stage 1, an omnidirectional inlet cyclone separator that can draw air from all directions was applied to collect bioaerosols larger than 10 μm in the collection fluid. In stage 2, an axial flow cyclone separator was used to collect bioaerosols sized between 2.5 and 10 μm in the collection fluid. In stage 3, bioaerosols smaller than 2.5 μm were collected on a filter and extracted in a solution through an elution process using a sodium phosphate buffer. To simulate the suspension of bioparticles including viruses that are attached to other particles in the atmosphere, the aerosol samples were prepared by coagulating aerosolized bacteriophages with Arizona test dust. Then, the coagulated particles were collected for 30 min using the developed bioaerosol sampler, and the samples collected in each stage were analyzed via polymerase chain reaction (PCR) method. The PCR analysis results confirmed that the high-volume bioaerosol sampler enables size-selective bioaerosol sampling even at a high airflow rate of 1000 L/min. The developed high-volume bioaerosol sampler will be useful in detecting viruses through PCR analysis because it can collect bioaerosols within a specific size range.