Particle Separation Efficiency Research Articles

Lab Scale Vibrating Screen Study on Operational Variables that Affect the Separation Efficiency

Vibrating screening is an equipment of simple design and execution, but its full description may be difficult to predict, considering that several variables can influence it. This work evaluates the effects of the independent variables: proportion of particles larger than the screen aperture size, average feed rate and g-force on the separation efficiency of coarse particles in a lab scale vibrating screening, where the material to be screened was phosphate rock, with density of 3.25 g/cm3 and particle size range of 0.6–600 μm. For this, a central composite design (CCD) was applied to quantify the main effects of the variables. As a result, the average feed rate was not relevant and the proportion of coarse particles and the g-force contributed positively to the increase of the efficiency. The point where the variables have their highest values, the maximum experimental efficiency was observed (94.93%).

Effect of inlet configuration on hydrocyclone performance

Inlet configuration is important parameter of hydrocyclones, which has great impact on the classification performance. The effects of inlet configuration on the precise classification were studied by computational fluid dynamics under various combinations of inlet diameter and inlet velocity. The results showed that a high sharpness of classification was achieved with specific inlet diameter and inlet velocity. The separation efficiency of the coarse particles by underflow significantly decreased when inlet had an oversize diameter owing to a stronger short-circuit flow. It is resulted from the chaotic flow and the stronger pressure gradient around the vortex finder. Meanwhile, a low separation efficiency of the fine particles by overflow was achieved when inlet velocity was high, which indicated a low sharpness caused by the overlarge centrifugal force.

Pneumatic jigging: Influence of operating parameters on separation efficiency of solid waste materials.

This article aims to provide insights into the factors that contribute to the separation efficiency of solid particles. In this study, a pneumatic jigging technique was used to assess the separation of solid waste materials that consisted of copper, glass and rubber insulator. Several initial experiments were carried out to evaluate the strengths and limitations of the technique. It is found that despite some limitations of the technique, all the samples prepared for the experiments were successfully separated. The follow-up experiments were then carried out to further assess the separation of copper wire and rubber insulator. The effects of air flow and pulse rates on the separation process were examined. The data for these follow-up experiments were analysed using a sink float analysis technique. The analysis shows that the air flow rate was very important in determining the separation efficiency. However, the separation efficiency may be influenced by the type of materials used.

Towards the design of unit operations to remove colloidal particles from hydrocarbons and fuels through aggregation and sedimentation

The presence of fine (submicron) particles in hydrocarbon streams is problematic due to their undesirable impact on product quality and their gradual deposition and fouling effects on equipment. By forming large aggregates that are subject to gravity settling, these particles can be removed. However, the particles are often coated with carbonaceous matter that may negatively influence their aggregation. In this study, submicron silica particles were coated with a layer of hydrocarbon materials, and then suspended in different types of organic solvent to examine their settling rates. The experiments showed that the coating caused quite different settling regimes in different types of solvent. A mathematical model was proposed to study the kinetics of the settling process. The results were used to evaluate the performance of current settling units. A specific modification was suggested to improve the efficiency of particle separation.

Redesigned t-PFF-v device fabricated with one-step anisotropic chemical wet etching process: enhanced separation efficiency for colloidal particles in continuous-mode

A pinched flow fractionation device with trapezoid-shaped pinched segment and cross-flow side channels (t-PFF-v) was redesigned and fabricated with a one-stop anisotropic chemical wet etching process and its enhanced separation capability was demonstrated for spherical polystyrene (PS) particles with diameter ranges of 2–8 µm. The tilted sidewalls and vertical focusing channels of the t-PFF-v device led to an improved separation resolution (Rm,n) via enhanced separation distance of PS particles at the pinched segment (Δxm,n) and reduced effluent particle distribution width (sn). Using this t-PFF-v device with Wp (pinched segment width) of 25 µm, PS particles with diameters of 4, 6, and 8 µm were simultaneously separated with good separation resolution (R4,6 = 3.2 and R6,8 = 3.4). Moreover, by adapting even smaller pinched segment width (Wp = 15 µm), PS particles with diameters of 2 and 4 µm, not well separated in the previous studies, were clearly separated with 9.5-fold improvement in R2,4 compared with the normal PFF device (n-PFF). The effects of inlet flow rate ratio (Q2/Q1) on the separation efficiency were also carefully investigated and provided additional insight on the separation processes within the pinched segment of t-PFF-v device. The drain flow through the cross-flow v-channels helps better alignment of particles at the sidewall of pinched segment and resulted in significantly reduced distribution of effluent particles, even under the operating conditions with low Q2/Q1 values.

Study of inlet temperature effect on single and double inlets cyclone performance

In this paper, a comprehensive study is performed in order to demonstrate the effect of the flow and particle temperature on cyclone performance. Three main characteristics of the low-mass-loading gas-solid cyclone separators, including: pressure drop, particle separation efficiency and natural vortex length are investigated. Eulerian-Lagrangian approach is employed to solve the unsteady Navier-Stokes and energy equations to model the flow of particles. Because of the strong swirling flow in cyclone, Reynolds stress transport model (RSTM) is used to calculate the Reynolds stresses. Numerical simulation is accomplished at a temperature range of 293–700K and four inlet velocities. Also, a comparison is conducted between two Stairmand high efficiency cyclones with the same dimensions, one with single inlet and the other with double inlets to declare the effect of the second inlet on cyclone performance. The analysis of results shows that the swirling flow becomes weaker for higher temperature cases and thus, flow pressure drop and particle separation efficiency is noticeably decreased. Increasing in temperature causes decrease in natural vortex length. Also, study of natural vortex length is performed for the studied range of temperature.

A pilot trial for fast deep desulfurization on MOF-199 by simultaneous adsorption-separation via hydrocyclones

Abstract Deep removal of organic sulfur from fuel has become an important issue worldwide in the field of energy and environment. In this work, a novel approach for efficient adsorption-desulfurization in which both the adsorption and separation processes were performed simultaneously was demonstrated in a two-stage hydrocyclones pilot trial. We applied mass-produced MOF-199 as the adsorbent and dibenzothiophene (DBT) dissolved in dodecane as the model fuel. The adsorption dynamics and the significant influences of the dosage of adsorbent, the inlet flow rate and the split ratio on the removal efficiency were investigated to match the simultaneous adsorption-separation processes. After optimizing the operating conditions, the ultimate DBT concentration in the outlet of the two-stage hydrocyclones was 8.79 ppmw, which was less than the regulatory target of 10 ppmw; the separation efficiency of MOF-199 particles was as high as 99.75% within 30 s at an initial DBT concentration of 50 ppmw and a dosage of MOF-199 of 5 wt.%. More importantly, MOF-199 can be successfully regenerated using H 2 O 2 oxidation at the laboratory scale. The exceptionally high removal efficiency, fast separation speed, low cost and simple equipment make this simultaneous adsorption-separation hydrocyclone process a promising deep-desulfurization method.

Enhancement of solid particle separation efficiency in gas cyclones using electro-hydrodynamic method

This paper investigates the feasibility of using electro-hydrodynamic forces to enhance the efficiency of solid-gas separation in cyclone separators. Electro-hydrodynamic forces are applied using electrostatic coating of particles on which the lateral forces are increased in the presence of a radial static charge. It is shown that these additional forces are larger than the centrifugal force. The experimental and theoretical results show that the proposed method enhances the efficiency by 33% for the particle sizes of 4 μm, and hence can be used as an enhancement to the conventional cyclone designs.

A Comparative Study on the Separation of Different‐Shape Particles Using a Mini‐Hydrocyclone

AbstractThe separation efficiency from water of different‐shape particles was studied experimentally using a mini‐hydrocyclone. Spherical and flaky (plate‐like) aluminum particles with the same particle size distributions were employed. Also, the effects of the feed flow rate and the temperature on the separation performance were studied. The results were investigated in terms of slurry recovery, total efficiency, and partition curves. The separation efficiency of the spherical particles increased with increasing particle size, temperature, and feed flow rate, as expected. The fishhook effect, as a noticeable phenomenon, was observed for the spherical particles. In case of the flaky particles, the separation showed an unusual behavior: The separation efficiency decreased with increasing particle size in the largest particle fraction, which has so far not been reported and addressed in this way.

Acoustophoretic separation of airborne millimeter-size particles by a Fresnel lens

We numerically demonstrate acoustophoretic separation of spherical solid particles in air by means of an acoustic Fresnel lens. Beside gravitational and drag forces, freely-falling millimeter-size particles experience large acoustic radiation forces around the focus of the lens, where interplay of forces lead to differentiation of particle trajectories with respect to either size or material properties. Due to the strong acoustic field at the focus, radiation force can divert particles with source intensities significantly smaller than those required for acoustic levitation in a standing field. When the lens is designed to have a focal length of 100 mm at 25 kHz, finite-element method simulations reveal a sharp focus with a full-width at half-maximum of 0.5 wavelenghts and a field enhancement of 18 dB. Through numerical calculation of forces and simulation of particle trajectories, we demonstrate size-based separation of acrylic particles at a source sound pressure level of 153 dB such that particles with diameters larger than 0.5 mm are admitted into the central hole, whereas smaller particles are rejected. Besides, efficient separation of particles with similar acoustic properties such as polyethylene, polystyrene and acrylic particles of the same size is also demonstrated.

Separation efficiency and heat exchange optimization in a cyclone

Abstract This work presents a study on a gas-solid cyclone separator used in a complex cement production plant. The objective of the study consists on the performance evaluation and optimization of the cyclone separator in terms of particle separation and heat transfer efficiencies, while keeping pressure losses under control. The thermal interaction is between two gas-solid mixtures, one feeded at 850 °C and the other at 600 °C, respectively. The solid phase consists, mostly, of calcium carbonate subsequently intended to the so-called baking process for the production of clinker and then cement. The main goal of the study is maximizing the separation efficiency, minimizing the temperature at the exit of the plant and maintain the pressure drop not far from its value in the running plant. In a previous study, the authors defined the suitable setup of the mesh, physical models and turbulence; the same setup has been adopted in the present work during all the optimization phase. Vortex finder length (initially of cylindrical shape), its conicity angle and the pressure losses are the parameters (independent variables), taken into account to optimize the separation efficiency and the temperature of the gas at the exit of the plant. The optimization process was started with the base case that replies the geometric shape of the plant in operation. A detailed overview of the classical and recent optimization methods, is included in the Appendix, together with a brief illustration of a general pattern concerning an optimal design procedure. The numerical approach, for all the cases, is based on implicit unsteady simulations using the Eulerian Multiphase model.

Role of Humic Acid in Enhancing Dissolved Air Flotation for the Removal of TiO2 Nanoparticles

The particle separation efficiency by flotation sharply decreases or even completely fails when the diameter of dispersed particles falls into the nanoscale. In the present laboratory work, humic acid was used to enhance the removal of TiO2 nanoparticles from suspension in a chemical coagulant-free dissolved air flotation process. Without humic acid, merely 63.8% of TiO2 nanoparticles were removed. For the humic acid-assisted dissolved air flotation, the pH of humic acid solution significantly influenced the removal efficiency: more than 90% of nanoparticles could be separated when the pH of the humic acid stock solution was acidic; however, the basic solutions resulted in rather poor performance. In the acidic solution, the fiberlike humic acid might form colloids through the attraction between hydrophobic moieties. They possibly acted as a fishnet and trapped nanoparticles, leading to the great measured bubble–particle attachment efficiency. In all the effluents, a low residual dissolved organic carbon ...

Analysis of the effect of counter-cone location on cyclone separator efficiency

Abstract This paper analyzes the possibility of optimizing the structure of cyclone separators through the application of an additional compartment in the form of a counter-cone. Analysis of studies published so far indicates that few of them concern such improvements for cyclone separators, and those that do focus solely on determining the effect of a counter-cone on the efficiency of solid particle separation. This paper also assesses the effect of a counter-cone on pressure drop. Furthermore, the risk of excessive agglomeration of particles in the lower area of the conical part of the cyclone due to the proposed structural modifications was assessed. Based on the obtained study results, was proposed a method for the determination of the optimum counter-cone location. Fifteen variants of geometric configurations of the counter-cone were tested using two study methods - Computational Fluid Dynamics (CFD) and experimental research. The Reynolds-averaged Navier–Stokes equations with the Reynolds stress turbulence model (RSM) were used in the analysis. Cyclone separators from a real industrial installation, i.e. a kiln gas bypass system for cement clinker burning, were used for the research. This allowed for additional validation of the numerical models used and parametrization of calculation and boundary conditions. The application of a counter-cone was found to benefit the basic parameter characterizing cyclone separators, i.e. separation efficiency.

Spiral microchannel with ordered micro-obstacles for continuous and highly-efficient particle separation.

Controllable manipulation of fluid flow is crucial for efficient particle separation, which is associated with plenty of biomedical and industrial applications. Microfluidic technologies have achieved promising progress in particle positioning depending on inertial force with or without the help of the Dean effect. Herein, we describe an inertial microfluidic system containing a spiral microchannel for various highly efficient particle separations. We demonstrated that Dean-like secondary flow can be regulated by geometric confinement in the microchannel. On the introduction of a library of micro-obstacles into the spiral microchannels, the resulting linear acceleration of secondary flow can be applied to remarkably enhance particle focusing in time and space. Further, multiple separating and sorting manipulations of particles including polymeric particles, circulating tumor cells, and blood cells, can be successfully accomplished in the dimension-confined spiral channels in a sheathless, high-throughput (typically 3 ml min-1), long-term (at least 4 h), and highly-efficient (up to 99.8% focusing) manner. The methodological achievement pointing to ease-of-use, effective, and high-throughput particle manipulations is useful for both laboratory and commercial developments of microfluidic systems in life and material sciences.

Modelling of Mercury Emissions from Large Solid Fuel Combustion and Biomonitoring in CZ-PL Border Region

Abstract Tightening of norms for air protection leads to a development of new and significantly more effective techniques for removing particulate matter, SOx and NOx from flue gas which originates from large solid fuel combustion. Recently, it has been found that combinations of these environmental technologies can also lead to the reduction of mercury emissions from coal power plants. Now the greatest attention is paid especially to the coal power plant in Opatovice nad Labem, close to Hradec Kralove. Its system for flue gas dedusting was replaced by a modern type of cloth fabric filter with the highest particle separation efficiency which belongs to the category of BAT. Using this technology, together with modernization of the desulphurisation device and increasing of nitrogen oxides removal efficiency, leads also to a reduction of mercury emissions from this power plant. The University of Hradec Kralove, the Opole University and EMPLA Hradec Kralove successfully cooperate in the field of toxic metals biomonitoring almost 20 years. In the Czech-Polish border region, comprehensive biomonitoring of mercury in bioindicators Xerocomus badius in 9 long-term monitored reference points is done. The values of mercury concentration measured in 2012 and 2016 were compared with values computed by a dispersion model SYMOS′97 (updated 2014). Thanks to modern methods of dedusting and desulphurisation, emissions of mercury from this large coal power plant are now smaller than before and that the downward trends continues. The results indicate that Xerocomus badius is a suitable bioindicator for a long-term monitoring of changes in mercury imissions in this forested border region. This finding is significant because it shows that this region is suitable for leisure, recreation, and rehabilitation.

A novel high-volume separation technology base on acoustophoresis for treatment of produced water in the oil and gas industry

A novel emulsion splitting separation technology has been developed using acoustic radiation forces to recover the dispersed oil phase from an oil water emulsion. Current separation technologies suffer from high energy costs, use of consumables, fouling, and limited efficiency in separation of micron-sized particles. Multi-dimensional ultrasonic standing waves are used to trap a dispersed phase in a fluid. The action of the acoustic forces results in clustering and coalescence of droplets. Upon reaching a critical size, they are continuously separated through enhanced buoyancy. A second mode of operation uses acoustic radiation forces to increase the average droplet size and reduce the sub-20 micron droplet concentration. Earlier work was presented at ICA 2013(Dionne [1]). New results are shown for prototypes with a 1x2, 3x4 and 6x6 inch flow chamber driven by 2 & 3 MHz PZT transducers operating at flowrates of 1L/h, 30L/h, and 227-1136 L/h, tested with produced water samples from four US locations. Measured separation efficiencies of over 90% have been documented as well as particle size shifts of >100 micron. The particle size shift is particularly appealing as it acts as a complimentary technology to existing oil & gas separation technology. [1] J. Dionne, B. McCarthy, B. Ross-Johnsrud, L. Masi, and B. Lipkens, “Large volume flow rate acoustophoretic phase separator for oil water emulsion splitting,” J. Acoust. Soc. Am., Vol. 133, No. 5, Pt. 2, May 2013, pp. 3237. [Work supported by NSF SBIR IIP- 1330287.]

Optimization design of separators for removing solid particles from main steam pipeline of high-parameter steam turbine

In this paper, particle separators with different structures are designed based on main steam pipe of an ultra supercritical steam turbine. With the employment of particle rebound model established through high temperature particle rebound experiment, systematic numerical simulations on the influence of particle trap structure, steam mass flow for transporting particles on separation performance and pressure loss characteristic of separation system are carefully conducted. Besides, the effect of particle separation system on the working performance of thermal system is also analyzed. Results show that particle separation efficiency of three traps increases with the increase of amount of steam for transferring particles first, which then stabilize after a certain value is reached, while pressure loss of particle separation system is basically constant. With a small amount of transporting steam, separation efficiency of 100μm particle in trap B can reach up to 78%, and pressure loss of the system is below 13kPa. Effect of particle separation system on the heat rate of 1000MW thermal system is less than 0.15%, which is well below the profits earned through the reduction of solid particle erosion to turbine blades. The result of this paper will provide new ideas for thoroughly solving erosion problem of high parameter steam turbine.

Designing vortex finder structure for improving the particle separation efficiency of a hydrocyclone

Abstract In this study, three types of vortex finder structures, namely Types A, B, and C, of 10-mm hydrocyclones were designed for improving particle separation efficiency. The Type A vortex finders had uniform but different thicknesses, and the Types B and C had extra conical shapes with different lengths on the outer surfaces. The velocity and pressure distributions in the hydrocyclones were simulated using computational fluid dynamics. The governing equations were coupled using the Semi-Implicit Method for Pressure Linked Equations (SIMPLE) algorithm, and the second-order pressure-strain coupled with the Reynolds stress model was used in the simulations. When the liquid velocity distribution was simulated, particle trajectories were traced on the basis of a Lagrangian frame considering the hydrodynamic interactions between liquid and particles. Calcium carbonate particles with a density of 2800 kg/m3 and a mean size of 17.8 μm were used as a particulate sample. The simulation methods were verified by comparing the simulation results with the experimental data measured using several selected hydrocyclones. The particle separation efficiencies observed using the different hydrocyclones were compared at an inlet velocity of 10 m/s and a split ratio of 0.6. A thicker vortex finder resulted in higher particle separation efficiency because a higher velocity is maintained in the cylindrical part, but it also resulted in reduced particle residence time and an increased pressure drop through the hydrocyclone. Installing conical structures on the outer surface of the vortex finders was beneficial for improving the particle separation efficiency and reducing the particle cut-size. The sequence of particle separation efficiency observed using the various hydrocyclones was Type C > Type B > Type A. Considering the separation efficiency, pressure drop, and particle cut-size simultaneously, Types B-II and C-II were the optimal designs.

A Lagrangian-Eulerian hybrid model for the simulation of industrial-scale gas-solid cyclones

We present a generalization of the Lagrangian-Eulerian hybrid model for the numerical assessment of poly-disperse gas-solid flows (Pirker and Kahrimanovic, Acta Mechanica 204, 2009) [1] to industrial-scale cyclones. The main idea of this hybrid model is to use a combination of a Lagrangian discrete phase model (DPM) and a two-fluid model (TFM) to take advantage of the benefits of those two different formulations. On the one hand, the local distribution of the different particle diameters, which is required for the gas-solid drag force, can be obtained by tracking statistically representative particle trajectories for each particle diameter class. On the other hand, the contribution from the inter-particle stresses, i.e. inter-particle collisions, can be deduced from the TFM solution. These then appear as additional body force in the force balance of the tracer particles. Furthermore, we apply sub-grid modifications to the TFM to account for the small unresolved scales in the case of coarse grids required for industrial-scale applications. The numerical model is applied to an industrial-scale gas-solid cyclone separator, where the impact of an apex cone is studied. Furthermore, we investigate the effect of agglomeration on the separation efficiency of the cyclone. The results show (i) that the apex cone increases the separation efficiency of the sub-micrometer particles but yields an considerable increase of the cyclone's pressure drop and (ii) an adequate modeling of agglomeration is required to correctly predict the separation efficiency of the sub-micrometer particles. Finally, the presented model requires considerably less computational resources compared to multi-fluid models, where each particle diameter class is represented by its own transport equations.

Analysis of the effects of temperature and the share of solid and gas phases on the process of separation in a cyclone suspension preheater

Abstract Most scientific papers discussing cyclone separators do not consider the effects of temperature or the share of the solid and gas phases on the efficiency of such devices. This article analyses the effect of these factors on the efficiency of solid particle separation, based on a cyclone separator that constitutes part of a suspension preheater. The operating conditions for this device allowed for a wide range of temperatures to be taken into account. The main research procedure was preceded by exploitation research conducted at an industrial installation. This enabled the correct reconstruction of the cyclones actual operating conditions. The multiphase flow inside the cyclones was analysed with computational fluid dynamics (CFD). Reynolds-averaged Navier–Stokes equations with the Reynolds stress turbulence model (RSM) were used in the analysis. The methods used in this paper for analysing the phenomena occurring inside the device allow for the conclusion that both the temperature and the concentration of solid particles have a significant effect on the effectiveness of a cyclone separator. The presented analysis may help to optimise the cyclones used in cyclone suspension preheaters, as well as traditional devices used solely for separation processes.