Separation Performance Of Hydrocyclone Research Articles

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 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%.

Fast prediction and control of air core in hydrocyclone by machine learning to stabilize operations

Operation stability significantly impacts hydrocyclone separation performance during wastewater treatment, sludge processing, and microplastic removal from water. The air core inside a hydrocyclone is an important indicator of operation stability. This paper presents a machine learning model designed for fast prediction and control of air core profiles. The model is built upon a modified graph neural network (GNN). It is trained by the data generated from a well-established and validated computational fluid dynamics (CFD) model. This GNN-based surrogate model has undergone two modifications to enhance its prediction accuracy. One is data smoothing, to mitigate the adverse effects of the drastic data change in spatial distributions. The other is the loss function modification to incorporate the air core information acquired by the CFD model. The predicted air cores are compared with the original GNN and random forest (RF) against the CFD results. It shows that the new surrogate model can reproduce air profiles and have higher accuracy than other models in predicting spatial distribution results among different error metrics. Furthermore, this surrogate model is combined with the genetic algorithm to optimize the air core. The proposed machine learning model framework offers a promising avenue for the prediction and control of hydrocyclones.

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.

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.

Effect of underflow diameter on the separation performance of natural gas hydrate desanding and purification under back pressure

Solid fluidization is a promising method for the development of marine hydrate resources. The back pressure makes it difficult to backfill the separated sand to the well bottom, resulting in a decrease in separation performance and serious failure of hydrocyclone. This study is intended to study the effect of underflow diameter on the performance of the hydrocyclone by computational fluid dynamics method. The results show that with the increase of back pressure, the split ratio basically decreases linearly, and the LAVV gradually increases. Under the same back pressure, the underflow diameter is larger, the pressure drop is smaller. No matter how large the underflow diameter is, the hydrocyclone may fail once back pressure exceeds 60 kPa. Under the same back pressure, the larger the underflow diameter is, the higher the desanding efficiency is, while the purification efficiency is opposite. When back pressure exceeds 60 kPa, the desanding efficiency drops sharply, while the purification efficiency remains basically unchanged. This study is applicable to downhole in-situ separation for solid fluidization of marine hydrate. The purpose of this study is to guide the structure design of hydrocyclone and the optimization of hydrate production process parameters.

Interaction effects of inlet velocity and apex diameter on the separation performance of two-stage cone hydrocyclones

Hydrocyclones are widely employed in industrial fields to separate particles. The interaction between the apex diameter and inlet velocity is important for the regulation of the two-stage cone hydrocyclone, but it is not clear. In this study, a gas–liquid–solid three-phase turbulence simulation method, which combines the volume of fluid method, the Reynolds stress model and the discrete element method (VOF–RSM–DEM) via open source software, OpenFOAM, and our in-house developed software, DEMms, is developed. The reliability and validity of this method has been verified by the experiment results. Then it is conducted to investigate the interaction effects of inlet velocity and apex diameter on the separation performance of two-stage cone hydrocyclones. Results show that there are intense interaction effects between the apex diameter and inlet velocity and the variations of cut size and Ecart probable with apex diameter and inlet velocity are not always monotonic.

Effect of cone section combination form on the separation performance of a biconical hydrocyclone

Cone section structure optimization is critical in improving hydrocyclone separation performance, and the combination of multiple cone sections has more advantages than a single cone angle. Here, CFD technology is used to simulate a biconical hydrocyclone with different cone section combinations. The influence of the combination form on internal multiphase flow motion was analyzed, and the influences of the structural parameters of double-cone hydrocyclone on separation efficiency was explored. The results show that when the upper and lower cone angles of the biconical hydrocyclone are constant and the cone section transition diameter is changed, the cut size decreases, total separation effectiveness increases, and the accuracy of separation improves with increasing transition diameter. When the cone section transition diameter is constant and the upper cone angle is changed, total separation efficiency and accuracy decreases and cut size increases as the upper cone angle increases.

Numerical study of the multiphase flows and separation performance of hydrocyclone with tapered cross-section inlet

Numerical study of the multiphase flows and separation performance of hydrocyclone with tapered cross-section inlet

Effect of the Position of Overflow Pipe with Mixed Spiral Structures on the Separation Performance of Hydrocyclones

Overflow pipes are important components of hydrocyclones. The overflow products can carry huge amounts of residual energy when being discharged. In order to take full advantage of the residual energy and enhance hydrocyclone separation performance, this research designed a novel hydrocyclone by adding static mixing units with spiral elements in the overflow pipe. This study performed numerical simulations to investigate the effects of the install position of the spiral structure on the separation performance and inner flow field of the hydrocyclone. It can be concluded that both tangential velocity and pressure are first enhanced and then reduced by the elevation of the spiral structure. When the spiral structure is installed 30 mm away from the overflow pipe bottom, because of the hindrance of spiral elements, the discharge of coarse particles with the overflow are fully decreased and the quality of overflow products are enhanced.

Influence of Feed Rate on the Performance of Hydrocyclone Flow Field

In order to clarify the influence of feed rate on a hydrocyclone flow field, numerical simulation was employed to model the influence of feed rate on the pressure field, velocity field, air column, turbulent kinetic energy, and split ratio. The results revealed that static pressure, tangential velocity, and radial velocity increased with an increase in the feed rate. When the feed rate at the inlet increases from 1 m/s to 5 m/s, the static pressure increases from 5.49 kPa to 182.78 kPa, tangential velocity increases from 1.97 m/s to 11.16 m/s, and radial velocity increases from 0.20 m/s to 1.16 m/s demonstrating that a high feed rate facilitated the strengthening separation of the flow field. Meanwhile, with the increase in the feed rate, the split ratio of the hydrocyclone decreased, indicating that the concentration effect of the hydrocyclone improved. Additionally, the formation time of the air column was reduced, and the flow field became more stable. Nevertheless, the axial velocity and the turbulent kinetic energy also increased with the increase in the feed rate, and the increase in the axial velocity reduced the residence time of the material in the hydrocyclone, which was not conducive to the improvement of separation accuracy. In addition, the increase in turbulent kinetic energy led to an increase in energy consumption, which was not conducive to the improvement of the comprehensive performance of the hydrocyclone. Therefore, choosing an appropriate feed rate is of great significance to the regulation of the flow field and the improvement of hydrocyclone separation performance.

Research on the Enhancement of the Separation Efficiency for Discrete Phases Based on Mini Hydrocyclone

The economic and efficient treatment of mixed media in offshore produced fluids is of great significance to oilfield production. Due to the small space and limited load-bearing capacity of offshore platforms, some mature multiphase media separation processes in onshore oilfields are difficult to apply. Therefore, high-efficiency processing methods with small-occupied space are required. Mini hydrocyclones (MHCs) are a potential separation method due to their simple structure, small footprint, and high separation efficiency (especially for fine particles or droplets). However, for discrete phases with different densities and sizes, the enhancement rule of the separation efficiency of MHCs is not yet clear. In this paper, numerical simulation methods were used to study the separation performance of hydrocyclones with different main diameters (including conventional hydrocyclones (CHCs) and MHCs) for discrete phases with different densities and particle sizes. Results show that MHC has the optimal enhancement range for oil–water separation when oil-droplet sizes are 60–300 μm, while the optimal enhancement range for silica particle and water separation is 10–40 μm. For other droplet/particle size ranges, the efficiency enhancement effect of MHC is not obvious compared to conventional hydrocyclones. By calculating the radial force of particles in MHC and CHC, the reasons for the enhanced efficiency of MHC are theoretically analyzed. The pressure drop of MHC is higher than CHC under the same feed velocity, which can be improved by connecting CHC with MHC. Additionally, the fluid velocity test experiments based on particle image velocimetry (PIV) were carried out to verify the accuracy of the numerical simulations. This study clarified the scope of application of MHCs to different discrete phase types, in order to provide a basis for the precise application of MHCs.

Numerical Simulation Investigation of Vortex Finder Depth Effects on Flow Field and Performance of Desanding Mini-Hydrocyclones

Sand has significant side effects on oil production and offshore platform processing system. Mini-hydrocyclones is a very important component to desanding operation system. However, even a slight modification on the structural parameter of hydrocylone might result in a significant influence on its flow field and separation efficiency. So, analysis on flow field characteristics and separation efficiency of the mini-hydrocyclones can help to optimize its structural parameters. In this work, five mini-hydrocycloness were designed, and flow patterns and particle separation ability of a mini-hydrocyclones with various vortex finder depths were investigated through Computational Fluid Dynamics (CFD) simulation method. The research shows that vortex finder depth has a significant influence on the separation function partition of mini-hydrocyclones. The deeper the vortex finder depth is, the larger the volume of pre-separation area, the smaller the volume of the main separation area and the bigger the energy consumption are. These characteristics are disadvantage to improve separation performance of hydrocyclone. Ratio (L0/D) of vortex finder depth (L0) to the hydrocyclone cylinder diameter (D) is about 1.0.

Effect of back pressure on the separation performance of a hydrocyclone

In industrial process applications, to shorten the process flow and use the residual energy of hydrocyclone overflow, the overflow outlet is often directly connected to the subsequent equipment, and the back pressure of the subsequent equipment inevitably affects the normal operation of the front-end hydrocyclone. Therefore, this paper uses numerical simulation to study the effect of overflow back pressure on the internal flow field and separation performance of hydrocyclones. The results show that increasing the overflow back pressure increases the total pressure drop of the hydrocyclone, has no significant effect on the internal radial pressure gradient, and only increases the energy consumption of the hydrocyclone. With the increase in the overflow back pressure, the solid phase yield of the underflow increases, the content of fine particles gradually increases, the content of coarse particles decreases, and the separation accuracy of the hydrocyclone decreases. • The effects of back pressure on the flow field were investigated. • The influences of back pressure on the separation performance were studied. • The particle size distribution of the products were analysed.

Experimental study of the separation performance of a hydrocyclone with a compound curve cone

The entrainment of fine particles in the underflow and coarse particles in the overflow is a well-known problem in separation using a conventional cylindrical–conical hydrocyclone that reduces the separation accuracy and efficiency. To address this problem, this paper presents a hydrocyclone equipped with a compound curved cone (the CCC hydrocyclone). The CCC hydrocyclone was experimentally compared with a hydrocyclone with a conventional straight cone (the CSC hydrocyclone) in terms of five separation performance metrics, namely, the split ratio, total separation efficiency, concentration and particle size of the products, and grade efficiency. To provide further guidance on the application of the CCC hydrocyclone in real-world production, the effects of three process parameters—the underflow apex diameter and the particle mass concentration and pressure of the feed—on the separation performance of the CCC hydrocyclone were investigated in depth. Moreover, the CCC hydrocyclone was successfully used in a real-world industrial application.

Flow field analysis and performance evaluation of a hydrocyclone coalescer

ABSTRACT Hydrocyclones are extensively applied in oil-water separation for fluid purification. However, it is difficult for a hydrocyclone to separate tiny oil droplets. Therefore, the coalescence of oil droplets plays an important role in enhancing the separation performance of hydrocyclone. In this study, an innovative hydrocyclone coalescer (HCC) was designed to enhance the separation of de-oiling hydrocyclone. The population balance model was carried out to simulate the distribution characteristic of oil droplet size in the HCC. High speed video was utilized to study the coalescence process qualitatively. Furthermore, an improved particle size analysis experimental system was designed to evaluate the coalescence performance quantitatively. The effects of inlet flow rate, oil concentration and water viscosity on the coalescence of oil droplets in HCC were analyzed. Results show that the optimum inlet flow is 3.9 m3/h, and the oil droplets with mean diameter 0–200 μm at the inlet of HCC can be enlarged to 502.54 μm at the outlet. When the viscosity of water increases from 1.03 mPa·s to 5.56 mPa·s, the mean diameter decreases from 502.5 μm to 382.4 μm. The HCC shows obvious coalescence performance under different operation and fluid parameters, which can contribute to enhancing the separation precision of hydrocyclones.

Investigation of optimal design and separation performance of the hydrocyclone with a vorticose involute-line diversion feeding body

As an important transport channel for multi-phase flow, the feeding body imposes significant effects on the formation of granularity layer and pre-separation of particles. In a conventional feeding body, particles are generally under a turbulent state and intensively collide with the wall surface, thereby leading to the decline in particle separation precision. In this study, a novel hydrocyclone with a vorticose involute-line diversion feeding body was designed, and meanwhile the feeding body was optimized in structure. By means of numerical analysis, the inner flow field and particle separation performance were examined. It was found that using the novel structure of the feeding body can effectively reduce the inner turbulence in the hydrocyclone, accompanied with the enhancement of flow field stability and particle separation precision. Compared with the conventional hydrocyclone, the content of fine particles in the overflow can be enhanced by 32.68% while that in the underflow can be reduced by 43.17% using the novel feeding body. To be specific, the quality efficiency and quantity efficiency of the novel hydrocyclone were 15.66% and 14.87% higher than that of the conventional hydrocyclone, respectively, exhibiting remarkable improvement. Finally, the effect of inlet flow rate on the separation performance of the novel hydrocyclone was investigated. Results show that fine particles moved gradually outwards with the increasing inlet flow rate, accompanied with gradually increasing content of fine particles in the underflow and the decline in the mass of coarse particles. The cutting capability can also be enhanced with the increase of the inlet flow rate. At an inlet flow rate of 4.1055 L/min, the separation precision reached a peak. The present conclusion can offer insightful guidance for the further development of novel hydrocyclones.

Particle image velocimetry for investigating the effect of liquid rheology on flow field of liquid–solid hydrocyclone

ABSTRACT Liquid rheology affects the separation performance of hydrocyclones. Sewage entering a de-foulant hydrocyclone with a reflux ejector (DFHRE) exhibits different rheological properties based on the source. In this study, particle image velocimetry is used to investigate the effect of liquid rheology on the overflow–suck–underflow effect of the DFHRE. Results show that the effects of the rheological properties, liquid concentration, and inlet velocity on the flow field are primarily reflected inside the locus of the zero vertical velocity at the cone section of the DFHRE. In addition, the overflow–suck–underflow effect becomes less prominent as the apparent viscosity increases. An increase in glycerin (Newtonian) concentration increases the total pressure drop, unlike an increase in polyacrylamide aqueous solution (PAM, non-Newtonian). Increasing the inlet velocity can enhance the overflow–suck–underflow effect in PAM owing to the lower drag force. This implies that the DFHRE can achieve an overflow–suck–underflow effect on fluids with a lower drag force and enhance the separation performance.