Hydrocyclone Performance Research Articles

Numerical simulations on the separation performance of two-stage mini hydrocyclones connected in series

ABSTRACT Conventional hydrocyclones (CHCs) exhibit limited effectiveness in separating fine oil droplets from produced fluids, constraining overall oil-water separation efficiency. Mini hydrocyclones (MHCs) with smaller main diameter can further enhance the separation efficiency of fine oil droplets. This study constructs a two-stage series separation system using two individual MHCs. Simulations were conducted to investigate the effects of split ratio, water content, and oil droplet size on the separation performance. The adaptability of the series system to these parameters was thereby obtained. Results indicate the optimal separation efficiency is achieved when the total split ratio of the series system is 48%. The two-stage series system has better adaptability to the water content, and the separation efficiency keeps more than 97% when the water content is 86–98%, while the separation efficiency is lower than 92% when the water content is 86% in a single-stage MHC. When the inlet oil concentration exceeds 10%, for oil droplet sizes less than 0.15 mm, the two-stage series system outperforms single-stage MHCs operating independently.

Study on the effect of particle shape on underflow entrainment in hydrocyclone

ABSTRACT The underflow entrainment of fine particles leads to a decline in the grading performance of hydrocyclones, which is reflected in the “fishhook” effect in grade efficiency curves. This occurrence cannot be explained by existing separation theories. The primary cause of underflow entrainment of fine particles was examined from the perspective of particle shape in this study. Experimental results showed that the degree of “fishhook” effect in grade efficiency curves was Glass frit > Quartz ≥ Mica. This suggested that the underflow entrainment effect of spherical particles is stronger than non-spherical particles. Furthermore, experiments involving mixed powders of different coarse and fine components showed that, when large particles were nonspherical and small particles replaced with spherical ones of the same proportion, the underflow entrainment of fine particles situation worsened. This demonstrated that the main factor contributing to underflow entrainment was the tracking characteristics of small particles. Using EDEM coupled with Fluent to calculate the movement of different-shaped particles in the same flow field, the relationship between particle tracking characteristics and shape were analyzed. The results showed that the tracking characteristics of nonspherical particles was significantly less than that of spherical particles.

Effect of column segment diameter ratio on flow field and separation performance of the composite column-cone hydrocyclone

To address the misplacement of fine particles in the underflow caused by structural defects in conventional hydrocyclones, a composite column-cone hydrocyclone (C-C hydrocyclone) was proposed, featuring a cone-column-cone structure. Computational Fluid Dynamics (CFD) techniques were employed to study the diameter ratio and various configurations of C-C hydrocyclone, assessing the impact on separation performance. Results indicated that increasing the column section diameter ratio from 0.5 to 0.7 reduced the cutting size by 22.96 %, enhanced sharpness by 9.87 %, and improved separation efficiency. These findings offer valuable insights for the design and application of C-C hydrocyclones based on specific requirements such as grinding classification and flotation operations.

Influence of inlet velocity on the separation performance of a combined hydrocyclone

Hydrocyclone separation exploits centrifugal force to differentiate particles based on their sizes and densities, yet challenges arise when small, dense particles and large, low-density ones settle at similar velocities. To address this, we propose a two-stage combined hydrocyclone for accurate separation. Using numerical simulations, we examine the internal flow field and performance of this system. Our findings reveal that the primary hydrocyclone achieves size-dependent classification, while the secondary one achieves density-dependent sorting. Increasing inlet velocity enhances separation efficiency and accuracy by improving flow field dynamics, albeit at the cost of increased energy consumption and material residence time. Thus, optimizing inlet velocity is vital for maximizing the separation performance and operational efficacy of the combined hydrocyclones.

A study on the classification performance of water-injection hydrocyclone

Aiming at the problem of fine particles entrainment in the underflow of hydrocyclone during the metal grinding classification process, a water-injection hydrocyclone was proposed to improve the classification efficiency. Through external injection of water on the wall surface of the cone section, the particles settling in the region were loosely graded so that the fine particles settled in the wall surface returned to the inner swirl again, thus reducing their entry into the underflow. Numerical simulation was used to explore the differences in the internal flow field characteristics and separation performance of the hydrocyclone after adding the water-injection structure. Then the industrial tests were conducted on the classification performance of the water-injection hydrocyclone. Numerical results showed that compared with the conventional hydrocyclone, the static pressure, tangential and axial velocity of the fluid inside the water-injection hydrocyclone increased, while the turbulence intensity decreased. The experimental results showed that with the increase of water-injection flow rate, the content of -74 μm particles in the underflow of water-injection hydrocyclone first decreased and then increased, and the comprehensive classification efficiency increased and then decreased accordingly. Compared with the conventional hydrocyclone, the content of -74 μm particles in the underflow of the water-injection hydrocyclone was reduced from 26.34% to 23.95%, and the comprehensive classification efficiency was increased from 69.22% to 73.03%, which mitigated the phenomenon of fine particles entrainment in the underflow.

Study on the Oil-Water Separation Performance of Axial-Flow Hydrocyclone Enhanced by Condensate Bubbles

Abstract Produced water is the main by-product of the oilfield extraction process. Due to its high emulsification degree and density close to water, micron oil droplets are inefficiently separated by ordinary cyclone, and it is difficult to meet the standards of external discharge and reinjection after treatment. In this study, micron bubbles were prepared by mixing hydrocarbon components as gas and passed into the cyclone separator to enhance the oil-water separation effect. After the bubbles entered the cyclone, due to the pressure environment inside, the heavier components in the bubbles were found to condense and precipitate from the bubble surface, while the lighter components did not undergo phase change. The heavy hydrocarbons condense and spread out in the bubble and form a condensate film, because the condensate and oil droplets belong to the hydrocarbon homologue is easier to capture the oil droplets. This technology realizes the modification of lipophilic and hydrophobic surface of the bubbles. After the oil removal experiments found that the traditional axial cyclone separator separation of 65%, through the ordinary bubble assisted separation efficiency of 74%, and through the preparation of condensate bubbles to enhance flotation can be raised to 89% of the oil removal efficiency. Therefore, the condensate bubble-enhanced cyclone separator oil-water separation has a good application prospect.

Study on the separation performance of a three-product hydrocyclone with overflow reseparation

This manuscript proposes a three-product hydrocyclone with overflow reseparation to reduce the particle misplacement in overflow, which achieves secondary separation by utilizing the after-energy of internal swirling flow. Numerical simulations and physical tests were applied to investigate the separation performance. The simulation results revealed that the coarser particles entrapped were effectively recovered by sideflow, the recovery of 20 μm particles in the overflow decreased by 16.71 % ∼ 23.09 % with significant fineness improvement compared with conventional hydrocyclone. The intensity of the internal centrifugal field decreased with the overflow separation chamber expanded, which resulted in an increased probability of particle misplacement during overflow. The test results revealed that the particle content of more than 20 μm in overflow was reduced by 2.44 % compared with conventional hydrocyclone, reducing the overflow separation chamber increased the sideflow ratio and solid phase yield, increased the difference in fineness between sideflow and overflow, and improved the narrow-grain separation performance.

An optimization framework for achieving optimal hydrocyclone's performance aligning with decision-makers' preferences

Previous hydrocyclone optimization often neglected interactions among key performance objectives, which limits hydrocyclone wide applications to meet increasingly diverse industry demands. This study proposes an optimization framework to identify the most suitable hydrocyclone design and operating conditions with conflicting key performance objectives. An advanced multi-objective evolutionary algorithm (PICEA-g) is employed to generate Pareto-optimal solutions that capture trade-offs among multiple conflicting objectives. A novel data-driven predictive algorithm, INFO-ELM, is introduced to establish nonlinear relationships between key variables and performance objectives, thereby accelerating the search for Pareto-optimal solutions by PICEA-g. Furthermore, a multi-criteria decision-making method (TOPSIS) is utilized to determine the optimal solution based on decision-makers' preferences, ensuring consistency between preference information and decision outcomes. The framework's effectiveness is validated across various separation scenarios using two decision-making strategies. This study offers a comprehensive approach to address trade-offs in hydrocyclone optimization, widening its application in diverse separation scenarios.

Comparing the Performance of Hydrocyclones and High-Frequency Screens in an Industrial Grinding Circuit: Part I—Size Separation Assessments

Comparing the Performance of Hydrocyclones and High-Frequency Screens in an Industrial Grinding Circuit: Part I—Size Separation Assessments

Separation characters of dewatering hydrocyclone with annular vortex finder based on particle image velocimetry and experiments

The development of non-thermal separation techniques can provide new ideas for efficient and low-consumption separation of oil–water mixtures. As a typical non-thermal separation equipment, the separation performance of hydrocyclone is limited by the short-circuit flow (SCF). In this study, an annular vortex finder hydrocyclone (AVFH) is proposed by the structural innovation of increasing the annular vortex finder (AVF) to solve the problem of SCF. The effects of AVF structure with different insertion depths on the flow field characteristics and separation performance of the hydrocyclone were investigated by particle image velocimetry experiments and performance experiments. The results indicate that the SCF can be significantly reduced by increasing the AVF structure. When the inlet velocity was 5 m/s, the SCF rate of AVFH-S was reduced to 0. The AVFH-S achieves a maximum separation efficiency of 84.71 %, which is 4.90 % higher than that of the VFH-C. Compared with the existing disc centrifuge process, the separation efficiency after AVFH-S treatment increased by 6.80 %. This study provides theoretical support for regulating SCF to improve the separation efficiency of hydrocyclone, and lays a foundation for the optimization and expansion of the application of non-thermal separation equipment.

Study on the separation performance of honeycomb cone hydrocyclone

ABSTRACT The entrainment of fine particles in the underflow and coarse particles in the overflow are well-known problems during separation using conventional cylindrical-conical hydrocyclone. In order to enhance the separation accuracy, the paper proposed a new type of honeycomb cone hydrocyclone and investigated its separation performance. Numerical simulations were conducted to study the effects of different structural parameters on the internal flow field, including the concave ball diameter db, the distribution position of concave balls Pb and the area occupancy ratio of concave balls Nb. Compared with conventional hydrocyclone, the turbulence intensity inside the honeycomb cone hydrocyclone is reduced, and higher separation accuracy is obtained. Better separation effect is found when the structural parameter db is 6 mm, Nb is 40%, and the concave ball is distributed in the upper part of the cone. The classification efficiency of particles smaller than 45 μm is increased by 7.86%.

Effects of composite structures on internal flow field and particle classification performance of hydrocyclone

ABSTRACT Hydrocyclones are commonly used solid – liquid separation apparatuses extensively adopted in various sorting industries owing to their unique advantages. However, the intrinsic constraints of their structures result in comparatively low-classification precision. Therefore, this study proposes a series of composite-structured hydrocyclones to augment their classification accuracy. Employing computational fluid dynamics techniques, this study provides a numerical analysis of hydrocyclones with varying structures, thus resulting in a series of valuable findings. Initially, the introduction of the composite structures effectively strengthened the centrifugal force in a manner directly proportional to the number of inlets. Internal turbulence provides effective turbulent scouring of the particles, simultaneously offering enhanced flow-field stability. Finally, the cutting ability and classification precision of the composite structures were substantially enhanced compared with those of traditional hydrocyclones. This was most evident in the structures that utilized four inlets, a parabolic cone section, and a thick-walled overflow pipe structure which resulted in superior product quality.

Novel insights into the effect of cone structure on the classification performance of dual-cone hydrocyclones

The classification process in hydrocyclones is affected by many factors, with the cone angle being recognized as a critical parameter determining the classification performance. In the context of recycling iron ore tailings, this paper primarily focuses on the influence of cone angles and their combination sequences on the classification performance of quartz particles within a dual-cone hydrocyclone through numerical simulations. The upper and lower cone angles were configured in 16 combinations to assess their respective impacts on classification. The results indicate that the upper cone angle primarily governs the pressure drop and tangential velocity, thereby controlling the centrifugal intensity and cut sharpness. Furthermore, the lower cone angle plays a pivotal role in determining axial velocity and particle enrichment ratio in the lower cone, thus influencing the cut size and grade efficiency. These findings should provide valuable guidance for the design and application of compound cone hydrocyclones, depending on specific requirements.

Reliability-based design of high-performance hydrocyclones: Multi-objective optimization, fabrication using 3D-printing and experimental analysis

In the literature, several works aim to improve the performance of hydrocyclones using geometry optimization. However, these approaches do not consider the uncertainties in the models, design variables, and parameters, which can lead to solutions that do not correspond to the expected results when applied to real systems. Considering that, the present work proposed a reliability-based optimization of the hydrocyclone dimensions using the Advanced Mean Value (AMV) technique associated with the Multi-Objective Differential Evolution (MODE) algorithm. For that purpose, the maximization of total efficiency and minimization of underflow-to-throughput ratio and Euler number were taken as objectives and constraints were set to ensure an acceptable performance of the hydrocyclone in the main aspects of the process. Some of the obtained devices were selected to be fabricated through an additive manufacturing technique (3D printing) and, after that, be experimentally tested. The optimization results showed that the reliability-based optimization affected the Pareto curves in two different ways: a shortening or a displacement of the curve in relation to the nominal one, depending on which constraints are being activated. The experimental results demonstrated that the hydrocyclones obtained by the reliable approach had a greater tendency to meet the set constraints in practice. Finally, hydrocyclones with great experimental performance were obtained considering separation efficiency, concentration capacity, and energy consumption.

Numerical and experimental study of inlet velocity effects on separation performance of hydrocyclones for purifying low-grade phosphate ore

Due to the scarcity of phosphorus as a strategic resource, there is a growing trend to extract and refine low-grade phosphate ore using hydrocyclones. This study focuses on purifying low-grade phosphate ore using a hydrocyclone, with experiments conducted to obtain data on inlet velocity, mass flow rate, and pressure of inlet and outlet. These measurements assess pressure drop, separation efficiency and accuracy, thereby validating the numerical simulation outcomes. The Mixture and RSM models are used to simulate and analyze the hydrocyclone's internal multiphase flow field and performance of separation at varying inlet velocities. Findings show that an inlet velocity ranging from 6 to 7 m/s results in over 90% separation efficiency, around 90% separation accuracy, and low energy expenditure. These research findings provide theoretical guidance for low-grade phosphate ore separation and purification using hydrocyclones.

Numerical Study on the Separation Performance of Hydrocyclones with Different Secondary Cylindrical Section Diameters

The particle motion behavior in hydrocyclones has received increasing attention, but the particle circulation flow has received relatively limited attention. In this paper, the particle circulation flow is regulated by changing the secondary-cylindrical section diameter to optimize the separation effect. The effects of secondary-cylindrical section diameters on flow field characteristics and separation performance are explored using the two-fluid model (TFM). The findings demonstrate that particle circulation flows are ubiquitous in the secondary-cylindrical hydrocyclone and are induced by the axial velocity wave zone. The increase in the secondary-cylindrical section diameter intensifies the coarse particle circulation and aggrandizes the coarse particle’s aggregation degree and aggregation region, leading to an increment in cut size. The circulation flow component can be regulated by adjusting the secondary-cylindrical section, thus improving the classification effect. An appropriate diameter of the secondary-cylindrical section facilitates improved particle circulation, strengthening the separation sharpness.

Research on the particle circulation flow and classification performance of multi-stage cylindrical hydrocyclones

The cylindrical hydrocyclone is widely used for coarse particle classification to suppress the misplaced fine particles in the underflow. Nevertheless, the unique flat bottom structure generates particle circulation flow, causing the misplacement of coarse particles in the overflow. A multi-stage cylindrical hydrocyclone is designed to regulate the particle circulation flow by shortening the particle radial settling distance. The particle circulation flow and classification performance of the cylindrical hydrocyclone and multi-stage cylindrical hydrocyclone are investigated by numerical simulations and physical tests. The numerical test results demonstrate that the multi-stage cylindrical hydrocyclone strengthens the circulation flow of 59.5 μm particles and 89 μm particles, and limits the circulation flow of 150 μm particles, increasing the enrichment ratio of 59.5 μm particles and 89 μm particles, reducing the enrichment ratio of 150 μm particles. The experimental results indicate that the multi-stage cylindrical hydrocyclone suppresses particle misplacement in the overflow and underflow with superior classification efficiency, sharper separation accuracy, smaller cut size, and higher solids yields.

Effect of Structural Parameters on the Performance of Axial-Flow Inlet Hydrocyclones for In Situ Desanding from Natural Gas Hydrate Mixed Slurry.

Structural parameters play a decisive role in the performance of hydrocyclones for in situ natural gas hydrate (NGH) recovery and desanding. In this paper, the effects of key structural parameters on its performance were investigated by numerical simulations and experimental methods. The results show that the most influential factors are the spiral pitch of the spiral inlet, the vortex finder diameter, and the spigot diameter. The second most influential factors are the spiral turn number and the cone angle. Other parameters have the least influence. Specifically, the NGH recovery efficiency and pressure drop increase, but desanding efficiency decreases as d0/D and the cone angle increase. The NGH recovery efficiency and pressure drop decrease and desanding efficiency increases as ds/D increases. Therefore, it is necessary to choose a suitable value to balance the efficiency and pressure drop to improve the performance, for example, selecting the appropriate diameter ratio of the vortex finder and spigot. The above results can be used for the engineering design of in situ separators in marine hydrate mining and further realize in situ desanding, NGH recovery, and sand backfilling.

Effect of separation space on the separation performance of cylindrical hydrocyclones

Cylindrical hydrocyclones have received considerable attention for the benefits of reducing misplaced fine particles, but less attention to the effect of separation space on separation performance. This paper investigates the effect of separation space on the flow field and separation performance of cylindrical hydrocyclone by integrating the cylindrical height and vortex finder depth as variables utilizing a TFM model. The numerical results suggested that the separation space affected the tangential and axial velocities of particles slightly, while a larger separation space implies an enlarged upward distance of particles moving with the internal swirling flow, increasing the probability of forming particle circulation flow. Accordingly, the coarse particle enrichment region moves toward the wall and bottom region by increasing separation space. The separation accuracy increases and the cut size decreases by increasing separation space, however, the separation effect deteriorates when the vortex finder depth is less than the inlet pipe height.

Vortex finder diameter and depth effects on the separation performance of hydrocyclone

This study performed the numerical simulation of the vortex finder (VF) diameter and depth effects on the separation performance of the hydrocyclone-type devices for multiphase fluid separation, namely the static pressure, pressure drop, split ratio, short-circuit flow, velocity field, and classification accuracy. The static pressure, pressure drop, and split ratio were found to be negatively related to the VF diameter. As the VF diameter increased from 0.26D2 to 0.56D2, the maximum static pressure dropped from 94483.56 to 26067.86 Pa, and the pressure drop was reduced from 93336.50 to 26408.69 Pa. Meanwhile, the steepness index increased with the VF diameter in a particular range. The results strongly indicated that an increased VF diameter led to reduced energy consumption and improved separation accuracy of the hydrocyclone, decreasing the tangential velocity, increasing the short-circuit flow, and disrupting the symmetry of the locus of zero vertical velocity (LZVV). The effects of the VF depth on the separation performance were as follows: with increasing VF depth, short-circuit flow and split ratio decreased, the steepness index increased within a specific range, and the symmetry of the LZVV gradually improved. This implies that increased VF depths can help enhance the separation performance of the hydrocyclone but excessively large VF depths would deteriorate it.