Vortex Finder Research Articles

Effects of deswirler position and its centre body shape as well as vortex finder extension downstream on cyclone performance

The performance of a cyclone is studied when changing the position of the deswirler in the vortex finder, its centre body shape and a downstream vortex finder extension. This is done with simulations applying a Reynolds stress model for the turbulence. An extension of the vortex finder (from 2.64 dvf to 6.8 dvf) has almost no effect on cyclone pressure drop or collection efficiency. Moreover, the extension does not affect the pressure losses in the vortex finder. The closer the deswirler is installed to the vortex finder inlet the more significant is its effects on cyclone performance. A streamlined ellipsoidal shape of the deswirler centre body is preferable to a cylindrical one since it leads to lower pressure losses. Installation of the deswirler with a streamlined ellipsoidal centre body 2.64 diameters downstream the vortex finder inlet reduces pressure losses in the vortex finder by 74% as compared to a standard set-up. This leads to a 32% reduction in total pressure drop without deteriorating the separation capability of the cyclone.

Experimental and numerical study of a hydrocyclone with the modification of geometrical structure

AbstractThis paper proposes two kinds of structure‐modified hydrocyclone that exhibit better performance than the traditional ones. In type‐1, in which the outer edge of the vortex finder is hexagonal, the separation efficiency increases by 18.1 % compared to the conventional hydrocyclone, while type‐3, with a hexagonal conical section, can save 49.7 % of energy. To determine the reasons for the improvement in performance, numerical simulations are conducted to observe the flow field inside the hydrocyclones. Tangential, radial, and axial velocities are all studied in this research according to the simulation results. The radial velocity has a close relationship with separation efficiency. Based on the analysis, the separation mechanisms of different types of hydrocyclones are proposed. Furthermore, the air core, which is captured by a CCD camera, as a factor correlative to the flow pattern is also supportive of the improvement. The smoke area, which has many small air bubbles around the vortex finder, is defined in this work. The existence of the smoke area has a negative influence on energy transfer and separation efficiency.

Role of vortex finder depth on pressure drop and performance efficiency in a ribbed hydrocyclone

Hydrocyclones are devices used in many chemical and mineral based process industries for separation of fine particles. To enhance the performance efficiency of hydrocyclone with optimum pressure drop several configuration of hydrocyclone is designed and developed. A new hydrocyclone with spiral rib was designed. In the present study, the effects of spiral rib on pressure drop and separation efficiency are investigated experimentally and effect of vortex finder depth of a ribbed hydrocyclone was analyzed. The experimental results showed that the spiral rib has a significant effect on pressure drop and separation efficiency. It is interesting to note that by using a rib in the cylindrical part of the hydrocyclone resulted in lower pressure drop and improved separation efficiency. The pressure drop decreases by 17.5% and total efficiency increases by 10.5% at a feed velocity of 5 m/s and at a vortex finder depth of 7.6 cm. Pressure drop and separation efficiency also affected by the vortex finder depth. In this study, four ribbed hydrocyclones with 6 cm, 7.6 cm, 9.8 cm and 12.5 cm vortex finder depth have been taken for the analysis. Separation efficiency is maximum for the vortex finder depth of 7.6 cm.

Performance of mini-axial hydrocyclones

Axial or uniflow hydrocyclones have been much less studied than the reversed flow hydrocyclones but can be a viable alternative by providing lower pressure drop losses for the same Reynolds number. An experimental and numerical study of a simple mini-axial hydrocyclone with a diameter of 5 mm has shown that the pressure drop characterised by the Euler number, for a given Reynolds number, is lower than for a reverse flow hydrocyclone. The split ratio was found to be dependent on the relative size of the inlet and outlet cross sectional area. Numerical modelling showed that the use of a tangential feed to simplify the hydrocyclone design, rather than using mechanical vanes, led to recirculating vortices and asymmetry in the flow field. The radial velocities were found to be much smaller than the axial or tangential velocities. In contrast, the RMS velocities were found to be of comparable in magnitude in all three axes. The flow field obtained suggests that the shape of the exits, the location of the vortex finder and reducing recirculation can assist in improving the separation efficiency of an axial flow hydrocyclone.

Research on the effects of operating conditions and inlet channel configuration on exergy loss, heat transfer and irreversibility of the fluid flow in single and double inlet cyclones

Entropy generation method is employed to scrutinize the exergy loss and entropy generation of the air flow during the cleaning process inside three conventional types of industrial cyclones, i.e. single inlet, conventional double inlet and spiral double inlet. Different mechanisms of the entropy generation including; direct, turbulent and thermal dissipations are studied. Results show that the presence of the second inlet decreases irreversibility. Spiral double inlet cyclone saves up to 12.33% of the flow exergy in comparison with the single inlet one, while for the simple double inlet cyclone this value is about 7.63%. The highest value of irreversibility is observed at the entrance region of the vortex finder. While, this value is lower in double inlet cyclones in comparison with single inlet one. Moreover, the interesting relation between the convection coefficient and irreversibility indicates that 75% increase in convection coefficient leads to a 5% reduction in averaged turbulent entropy generation.

Particle size cut performance of aerodynamic cyclone separators: Generalized modeling and characterization by correlating global cyclone dimensions

To generalize the characterization of particle-size cut performance for aerodynamic cyclones, a data-driven modeling approach using two varied correlating strategy Ψ0.5=Cc1/2dp0.5/D and Stk0.5=(Ccρpdp0.52vi)/(18 μD) was proposed. This approach correlated the global influencing parameters including cyclone dimensions, operating conditions and multiphase properties which have not ever completely included before. The proposed models integrated the external geometrical dimensions (cyclone inlet area (ab/D) and vortex finder diameter De/D) into a annular Reynolds number Rea=ρgQ(D-De)/[μ(ab)], and used a special body dimensionless parameter DB/D derived from an equivalent volume method to characterize effect of the cyclone body dimensions: vortex finder length S/D, cyclone height H/D, cylinder height h/D and particle outlet diameter B/D. Results showed that the proposed Ψ0.5–based correlation improves the predictive ability and generalization performance compared to the other corresponding theoretical and regression models. Furthermore, the influence of cyclone dimensions and operating parameters on particle cutoff size was quantitatively addressed based on the proposed model. The result may provide a reference for performance assessment, design improvement and global optimization of aerodynamic cyclones applied both industrial process and aerosol sampling.

Numerical investigation of effects of inner cone on flow field, performance and erosion rate of cyclone separators

Abstract Gas cyclones have many industrial applications for separation of solids and liquids from gases. The geometry of the cyclone is the most influential parameter for its performance. This study investigates the effect of presence of an inner cone located at the bottom of the cyclone on the performance of the cyclone separator. Several CFD simulations in cyclones with inner cones with different diameters and heights were performed using the Reynolds stress turbulence model (RSM). The collection efficiency of the cyclone was studied using the Eulerian-Lagrangian approach. The results showed that the maximum tangential velocity is 1.6–1.7 times the inlet velocity. On the other hand, in the radial sections crossing the inner cone, the gradients of the axial and tangential velocities are zero. The maximum axial and tangential velocities occurred in the region between the top of the inner cone to the vortex finder. It was found that by increasing the inner cone height at constant diameter, the cyclone collection performance improves. An increase in the diameter of the inner cone, however, leads to a decrease in the cyclone performance. In overall, with an increase in the inner cone height and diameter, the pressure loss decreases. Finally, the erosion study was conducted using the Det Norske Veritas (DNV) erosion model. It was found that the value of coefficient of restitution affects the predicted erosion rate. In addition, the collection efficiency decreases when the erosion effect was included in the CFD model especially for higher velocities.

STUDI EKSPERIMENTAL PENGARUH KECEPATAN ALIRAN MASUK, SPLIT – RATIO DAN DIAMETER VORTEX FINDER TERHADAP UNJUK KERJA LIQUIDLIQUID CYLINDRICAL CYCLONE (LLCC) SEPARATOR

The large number of ports in Indonesia generate a lot of waste oil that contaminate the ocean around the port. However, the pollution prevention is not supported by a good facility. Hydrocyclone separator can be used as an alternative to supporting conventional separataor technologies such as vessel type separator or gravitational based separator to prevent the waste oil pollution. The purpuse of this study is to determine the effect of split ratio, inlet mixture velocity, and vortex finder diameter on the performance of the liquid-liquid cylindrical cyclone (LLCC). Oil (Kerosene) and water were selected as the working fluid and a red color (dye) was given to the oil to enable visualization . Performance of LLCC determined from watercut that produced from separation process. The examined inlet mixture velocity are 0.7 m/s, 0.9 m/s and 1.1 m/s with split-ratio 5%, 15%, 30%, 45%, 60%, 75% and 90%. . All of them are tested with vortex finders that have diameters 18 mm, 22 mm and 27 mm with 0 mm depth. The oil volume fraction inlet is kept constant at 25%. The result showed that LLCC was capable to separating oil-water mixture and produced watercut on underflow reaches 100%. The increasing of split-ratio will increase the watercut until reached the maximum value for all diameter of vortex finder. The condition when the oil content begin to move to the underflow on certain split-ratio is called oil drag. The split-ratio that used before oil drag occurs is called Optimum Split Ratio (OSR). LLCC should operated on OSR to obtain the best performance. The OSR is shifted to the higher split-ratio for higher inlet mixture velocity. The increasing of vortex finder diameter did not change LLCC performance significantly.

Industrial Application of Valuable Materials Generated from PLK Rock-A Bauxite Mining Waste

PLK rock classified in to two products after a selective grinding to a particular size fraction. PLK rocks ground to below 45-micron size which is followed by a classifier i.e. hydrocyclone. The ground product classified in to different sizes of apex and vortex finder. The pressure gauge was attached for the measurement of the pressure. The production of fines is also increasing with increase in the vortex finder diameter. In order to increase in the feed capacity of the hydrocyclone, the vortex finder 11.1 mm diameter and the spigot diameter 8.0 mm has been considered as the best optimum condition for recovery of fines from PLK rock sample. The overflow sample contains 5.39% iron oxide (Fe2O3) with 0.97% of TiO2 and underflow sample contains 1.87% Fe2O3 with 2.39% of TiO2. The cut point or separation size of overflow sample is 25 μm. The efficiency of separation, or the so-called imperfection I, is at 6 μm size. In this study, the iron oxide content in underflow sample is less than 2% which is suitable for making of refractory application. The overflow sample is very fine which can also be a raw material for ceramic industry as well as a cosmetic product.

The Classification Performance of a Three-Product Cyclone

Conventional (two products) cyclone have been widely used for classification in most mineral plants. But it is hard to satisfy the requirements of some productions by changing the parameter, such as cylindrical length and cone angle. In this paper, a three-product cyclone was developed and tested for recovery of the solid particles, which was composed of a primary cylinder and a secondary cyclone. Most of the fine particles were separated in the primary cylinder of the three-product cyclone by over flow, in order to reduce the particle size distribution before the separation of second stage. The remaining particles would be further classified by the secondary cyclone of the three-product cyclone. The design and operation of the three-product cyclone was systematically studied, and the size distribution have been analyzed of the three produces. The influence of the major parameters of cyclone, such as the spigot diameter, vortex finder diameter, and vortex finder length, on the solid recovery were investigated. Meanwhile, the regression models of the solid percent of the cylinder overflow, the cyclone overflow, and the cyclone underflow were developed through computer fitting analysis, which fitted well with the experimental values of solids recovered in the three products. The application of the regression models on the three products was proposed.

Cyclone separation in a supercritical water circulating fluidized bed reactor for coal/biomass gasification: Structural design and numerical analysis

A new concept of a supercritical water (SCW) circulating fluidized bed reactor is proposed to produce hydrogen from coal/biomass gasification. The cyclone is a key component of the reactor system. In this paper, cyclones with a single circular inlet (SCI) or a double circular inlet (DCI) were designed to adapt to the supercritical conditions. We evaluated the separation performance of the two cyclones using numerical simulations. A three-dimensional Reynolds stress model was used to simulate the turbulent flow of the fluid, and a stochastic Lagrangian model was used to simulate the particle motion. The flow fields of both cyclones were three-dimensionally unsteady and similar to those of traditional gas–solid cyclones. Secondary circulation phenomena were discovered and their influence on particle separation was estimated. Analyzing the distribution of the turbulence kinetic energy revealed that the most intensive turbulence existed in the zone near the vortex finder while the flow in the central part was relatively stable. The particle concentration distribution was non-uniform because of centrifugal forces. The distribution area can be divided into three parts according to the motion of the particles. In addition, the separation efficiency of both cyclones increased with the inlet SCW velocity. Because of its perturbance flow, the DCI separator had higher separation efficiency than the SCI separator under comparable simulations. However, this was at the expense of a higher pressure drop across the cyclone.

Effect of vortex finder dimension on holdup mass and heat transfer rate in cyclone heat exchanger-CFD approach

This work investigates the effect of vortex finder dimensions on solid cyclone heat exchanger using Reynolds stress turbulence model (RSTM) in CFD code FLUENT 12. Seven cyclones were tested to find the holdup mass and amount of heat transferred from the inlet gas to solid particles. Tangential and axial velocity of cyclone reduces with increase in vortex diameter whereas increase in vortex finder length reduces tangential velocity slightly and not much variation is observed with axial velocity. The experimental data used for the validation of simulations were obtained from the literature study. Previous works done in varying the dimensions of vortex finder does not predict the holdup mass and heat transfer rate in cyclone. This work presents effect of vortex finder dimensions on holdup mass and heat transfer rate on solid cyclone heat exchanger. Holdup mass and heat transfer rate decreases with increase in both vortex finder diameter and vortex finder length. Results indicate that change in vortex finder diameter has more impact of about 25% to 48% than change in vortex finder length on holdup mass and about 3% to 5% on heat transfer rate.

The CFD Simulation of Cyclone Separator without and with the Counter-cone in the Gasification Process

The performance of cyclone separator as the ash trapper in the gasification system was studied through the Computational Fluid Dynamic (CFD) using the finite volume method. The ash trapper system is important part due to the effect on the gasification process, in particular on the quality of Syngas (Synthesis Gas). Therefore, the aim of this study is to find the suitable of the cyclone separator in the gasification apparatus that can separate the syngas and particulates. The CFD simulation was performed to determine the effect of adding the counter-cone in the cyclone separator to the trend of the efficiency of ash separation, speed profile, and pressure drop in the gasification process. The Reynold Stress Model (RSM) was employed for the for swirl flows modelling accuracy. The efficiency of ash separation was predicted by using the flow velocity in the cyclone separator and the pressure drop in the vortex finder. Discrete Phase Model (DPM)-one-way coupling was used to predict the efficiency of collection. The results of this simulation show that by adding the counter-cone in the cyclone separator increasing the number of particulates trapped and the distribution efficiency of particle diameter. The cyclone separator with the counter-cone can trap the particle diameter less than 1 micro meter (μm) while the cyclone separator without the counter-cone cannot.

Effect of cylindrical section length and regression model of Euler number as correlated with vortex finder and cone lengths of a hydrocyclone

This research was made up of two parts: experimental results and a regression model. First, how the proportions of the cylindrical section affected separation efficiency of a 40 mm hydrocyclone was studied. The effects of cylindrical section lengths of 60, 80 and 100 mm were investigated. The tested suspension was a mixture of silica and water. The silica particles had an average size of 9-10 µm and the solid concentration of 0.5% w/v. A feed-flow rate of 1 m3/hr was operated with the flow ratio of 0.1. Experimental results showed that a shorter cylindrical section length led to higher separation efficiency. The best separation efficiency, up to 84.06%, occurred with a cylindrical section length of 60 mm, vortex finder length of 40 mm and conical section length of 200 mm.

Small Cyclones with Conical Contraction Bodies

The performance (i.e., cyclone pressure drop and particle penetration curve) of small cyclones with conical contraction bodies was investigated, with the cyclone used either as the size-selective inlet of a miniature/compact particle sensor/monitor or as a personal particle sampler. Prototype cyclones having inner bodies with conical contraction angles of 0°, 15° and 30° were constructed, and their performance was evaluated at various operational flow rates (viz., 1.0–7.0 L min–1); the results indicate that a cyclone with a high body contraction angle is capable of collecting smaller particles than one with a low contraction angle at the same cyclone pressure drop. The effect of the vortex finder insertion length on the cyclone’s performance was also studied and was found to be negligible. A linear relationship between the dimensionless particle cut-off size and the annular flow Reynolds number, Reann (in the log-log plot), could be found for the studied cyclones with characteristic cyclone velocity, calculated with the assumption of conservation of angular momentum for the swirling flow in a cyclone. Compared with previous studies, cyclones with conical contraction bodies have an advantage during lower pressure drops (up to 50%) for the same dimensionless particle cut-off size.

Numerical analysis on the effect of the vortex finder diameter and the length of vortex limiter on the flow field and particle collection in a new cyclone separator

There are many geometric and operational parameters that affect the performance of a cyclone separator, including the geometry and the length of the vortex within the cyclone. In this work, a Compu...

Effect of vortex finder dimension on holdup mass and heat transfer rate in cyclone heat exchanger-CFD approach

Effect of vortex finder dimension on holdup mass and heat transfer rate in cyclone heat exchanger-CFD approach

Application of Deswirl Device in Cyclone Dust Separator

The experimental investigations of the vortex flow inside the vortex finder (outlet duct) of the cyclone dust separator have been carried out. Preliminary study from the visualization experiment has been performed and discovered vortex instability inside the conventional vortex finder. In order to minimize the instabilities, the streamlined entry shape was inserted at the vortex finder entrance and the results showed remarkable improvement of the vortex flow instability inside the vortex finder. The velocity measurements of two main components of velocity were performed using a laser-Doppler anemometry at the cyclone vortex finder outlet. The experiments were conducted at a constant flow rate of 0.0246m3/s with the vortex finder diameter of 64mm and with several types of entrance configuration in order to improve the cyclone performance and to reduce the losses. The use of deswirl devices inside the vortex finder significantly reduced pressure drop and energy losses.

Alloy Selection for a Cofired Circulating Fluidized Bed Boiler Vortex Finder Application at 880 °C in a Complex Mixed Mode Corrosion Environment

X-ray diffraction and scanning electron microscopy (SEM) were used on a corroded industrial-scale circulating fluidized bed (CFB) boiler vortex finder (VF) 253MA alloy plate material to identify the dominating corrosion products and to enable a qualified selection of candidate alloys for the long-term, full-scale exposure study. Alloys 253MA, 310S, 800H/HT, Alloy DS, and Alloy 600 were chosen, and the alloy plates were exposed to the CFB boiler combustion atmosphere having an average temperature of approximately 880 °C, consisting of a moist globally oxidizing gas, burning hydrocarbons, CO2, CO, SO2, HCl, NH3, N2, alkali species, and erosive particles. The exposure times used in this study were 1750, 8000, 12000, and 16000 operating hours. After exposure, the alloy samples were cut, and cross-sections were dry-polished and analyzed with an SEM-backscatter electron detector (BSD) setup to quantify material loss and penetration depth of the corrosion attack. This work suggests two novel concepts: heavily af...

Effects of Cyclone Vortex Finder and Inlet Angle on Solid Separation Using CFD Simulation

Renewable energy is energy that is collected from renewable resources such as sunlight, wind, rain, tides, waves, geothermal heat and biomass. Biomass is alternative fuel which can be combusted to obtain electricity in various industries. Inorganic compound commonly found in ash is associated with the product gas after the combustion. The device that is widely used to separate the ash out of product gas is cyclone due to the simple construction, low maintenance cost and high reliability which making use of centrifugal force. Since conventional cyclone separators cannot separate solid particles with a high performance, the separation of particles in different novel cyclone shapes have been investigated in this study via three dimensions computational fluid dynamics (CFD). The computational meshes with high resolution of approximately 170,000-190,000 cells and (RNG) k- ε model are used for flow analysis of the cyclones. The simulation results have been accurately compared with the experimental results from Azadi et al. [1]. Then, the parameters in consideration are the diameter of gas outlet (vortex finder) and the angle of inlet with the inlet velocity of 15 m/s and solid volume fraction of 6×105.