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An attempt has been made to develop a non-intrusive and robust technique for online detection of roping in hydrocyclones using commercially available vibration-based sensors. A 50.8 mm diameter hydrocyclone was operated with two different silica slurry size distributions till roping was achieved in the underflow. Vibration signals were captured simultaneously at the spigot region for various operating conditions. Empirical Mode Decomposition (EMD) was applied to the raw vibration signal for extracting Intrinsic Mode Function (IMF) within the frequency range of the natural frequency of the hydrocyclone. Subsequently, Power Spectral Density (PSD) and frequency spectrum were computed along the axial direction. The Grms (square root of the area under PSD) and peak frequency values were found to be different for the spray and rope discharge which were used for detecting roping conditions. The differences were considered to be associated with the changes in the axial velocity fluctuations of the air core at the spigot region. Further, a flowchart has been proposed based on the methodology suggested in this work, which has the potential for online detection of roping in the hydrocyclone. [ABSTRACT FROM AUTHOR]

Hydrocyclones are widely used in the separation of two-phase immiscible mixtures. In various application scenarios, three-phase hydrocyclones (3PH) are often urgently needed. In this work, the typical 3PHs are classified into six categories according to their structural characteristics. A comprehensive analysis of their structural feature, design points and processing difficulties are carried out to provide guidance for the design of 3PH structure. On this basis, the technical and economic analyses are conducted based on operating parameters, separation performance and pressure loss. Furthermore, the current problems and future development directions of the 3PH separation technology are summarized. Hydrocyclones mounted in series are suitable for application scenarios with low requirements for floor space and energy consumption. The 3PH of constructing axially adjacent two-stage cyclone chambers is applicable for long and narrow spaces such as downhole separation. The 3PHs with two radially nested cyclone chambers or one independent cyclone chamber are applicable to limited spaces such as offshore platforms. Considering the comprehensive performance of different 3PHs, the 3PH with a single three-phase cyclone chamber is more recommended in practical applications. The analysis results can provide theoretical and technical support for the design, optimization and technical promotion of high-efficiency 3PH separation technology. [ABSTRACT FROM AUTHOR]

The work conducted flow field analysis of a typical hydrocyclone (φ500 type) in the Coal Processing Plant using CFD simulation, including hydrocyclone modeling, flow field development, static pressure distribution, three-dimensional velocity, and air column development. Besides, the effects of influential factors on the classification effect of hydrocyclone were studied. On this basis, a novel hydrocyclone model was developed and simulated for the ultrafine classification of coal slurry. The static pressure and velocity in the typical hydrocyclone have good symmetry and certain regularity. Decreasing the overflow pipe diameter and cone angle, while increasing the underflow pipe diameter, cylindrical section height, and feed rate will increase the classification efficiency of hydrocyclone. The novel hydrocyclone designed of annular feeding, small cone angle, and large cone bottom reduces energy consumption, decreases classification size, and improves classification accuracy. CFD simulation results show that the novel hydrocyclone has higher classification efficiency and smaller classification size over the typical hydrocyclone. The novel hydrocyclone develops an excellent ultrafine classification effect of coal slurry and provides a prospective approach for the industrial application of hydrocyclone in the fine coal ultrafine classification process. [ABSTRACT FROM AUTHOR]

A semi-industrial scale hydrocyclone with a 250 mm internal diameter was used to concentrate medium-grade celestine ore (75%–85% celestine) from the Montevive deposit of Granada (Spain) using a dense ferrosilicon (FeSi) medium. For this purpose, a Box–Behnken factorial design (BBD) was carried out, with the response variable being the Sr concentration measured by X-ray fluorescence (XRF), as well as the concentration of celestine measured by X-ray diffraction (XRD) of the mineral collected from the under (sunk) stream of the hydrocyclone. The experimental factors to be optimised were the density of the medium in the mixing tank (water, FeSi, and feed mineral) varying from 2.7 to 2.9 kg/L, the hydrocyclone inlet pressure from 0.8 to 1.2 bar, and the hydrocyclone inclination (from 15° to 25° from the horizontal). The range of densities of the dense medium to be tested was determined from previous sink–float experiments using medium-grade ore, in which the distribution of mineral phases with different particle size fractions was determined. To evaluate the separation behaviour, the following parameters were considered: the enrichment ratio (E), the tailings discarding ratio (R), and the mineral processing recovery (ε). From the factorial design and the response surface, the optimum parameters maximising celestine concentration in the under stream (78%), were determined. These optimised parameters were: a density of 2.75 kg/L for the dense medium, an inlet pressure of 1.05 bar, and a hydrocyclone inclination varying from 18° to 20°. Under these conditions, a 94% recovery of celestine (68% Sr) can be achieved. These results show that medium-grade celestine ore, accumulated in mine tailings dumps, can be effectively concentrated using DMS hydrocyclones and that the operating parameters can be optimised using a factorial experiment design. This study can contribute to reducing overexploitation of strategic mineral resources, avoiding blasting and environmentally damaging clearing, by applying a simple and sustainable technique. [ABSTRACT FROM AUTHOR]

Harmonization in the analytical framework is needed to detect, define and further categorize plastics released into the environment. In the range of particles smaller than 200 μm, hydrocyclones (HCs) have proven their capacity in removing microplastics efficiently by offering technical advantages at low operational costs. This publication aims to expand scientific knowledge by introducing four commercially available, low-priced microplastics to a pilot-scale HC setting. The physicochemical characteristics of particles as well as the separation efficiency of the test rig were investigated in depth. Particles with a density of >1000 kg/m3 passed the primary vortex and were discharged into the underflow, allowing us to employ standard mode operation. Particles with a density of <1000 kg/m3 entered the secondary vortex and were removed through the overflow. As expected, separation efficiencies were found to be higher for particles revealing a greater density difference when compared with the mobile phase water. Furthermore, an increase in the inlet volume flow revealed significant positive impacts on the separation efficiency for three plastics to a certain threshold. Data on standard and reverse mode operations presented in this publication can lay out an important source for the harmonization and standardization of future HC research, with the goal of overcoming plastic pollution by developing economically competitive separation processes. [ABSTRACT FROM AUTHOR]

A method to improve the classification performance of the cyclone was proposed by modifying the cone section of the conventional cyclone to address the problems of low classification accuracy and high operating energy consumption. The influence of linear, parabolic, and hyperbolic conical structures of cyclones on the internal flow field characteristics and separation performance was presented through numerical calculation methods. The numerical results show that using a parabolic cone can reduce the tangential and axial velocities of the cyclone, reduce the probability of turbulence, and effectively improve the stability of the flow field. The internal flow field of the hyperbolic cone is unstable, which is not conducive to the smooth operation of particles. The zero speed envelope surface of the parabolic cyclone moves outward, increasing the space for fine internal swirling flow and allowing for sufficient separation of fine particles, resulting in a certain improvement in classification accuracy. Compared to conventional and hyperbolic models, parabolic cyclones have lower turbulence intensity and effectively improve particle stability* At the same time, the steepness index of parabolic cyclones has been increased from 0. 61 to 0. 72, greatly improving the classification accuracy of cyclones. Due to the increase in separation space, the cutting particle size has slightly increased. [ABSTRACT FROM AUTHOR]

When the oilfield enters the middle and late stages of development, the moisture content of the produced liquid rises sharply. The primary problem that needs to be solved in the later stage of development is how to reduce the water content and improve the recovery rate. Hydrocyclone technology, gravity separation technology or other oil-water separation processes are used for downhole oil-water separation to achieve pre-separation of the moisture liquid downhole, so as to produce a lower water-water mixture, which has great application prospects for high water-cut oilfields. Through the brief analysis and summary of the research status of downhole oil-water separation device, the problems and challenges of the current downhole oil-water separation device were pointed out, and the prospect was made to provide a certain reference for its development. [ABSTRACT FROM AUTHOR]

In response to the issue of resource waste caused by the inability to recover and utilize microfine low-grade gold in the sulfur separation operation process of cyanide tailings in a gold production enterprise, a systematic experimental study was conducted. Based on the existing sulfur separation system, cyanide tailings and sulfur concentrate were used as experimental objects to test the gold recovery conditions of the technical scheme, forming a technical scheme for producing high-grade gold and sulfur concentrate and low-grade gold and sulfur concentrate through the enrichment of cyanide tailings by the existing sulfur separation system and further classification with a hydrocyclone. The scheme has the advantages of low cost and easy implementation for industrialization. After on-site transformation, two products were produced: high-grade gold and sulfur concentrate with a gold grade greater than 3.0 g/t and a sulfur grade greater than 46.5 %,and low-grade gold and sulfur concentrate with a sulfur grade greater than 46.5 %,which maximized the economic benefits. [ABSTRACT FROM AUTHOR]

• Eddy leaching technique was developed to treat heavy metal-contaminated soil. • Concentration of heavy metals in soil reduced as particle size increased. • Highest separation efficiency of hydrocyclone was 84.7%. • Enhanced desorption of heavy metals by eddy leaching compared to OAPE. An eddy deep leaching technology was developed in this paper to address the challenge of treating heavy metal contaminants in industrial mining areas. The desorption effect of As, Cd, Sb and Pb was investigated utilizing chemical leaching and physical eddy techniques. It was found that the heavy metals concentration increased with decreasing particle size. The highest proportion of Cd in the form distribution of soil was in the bound to iron and manganese oxides, while the maximum proportion of As, Sb and Pb were in the residual. The optimal solid-liquid ratio of the hydrocyclone was 1:20, and the corresponding separation efficiency and flow rate were 84.7% and 1.76 m3/hr, respectively. The grade efficiency of soil particle separation increases with particle size and exceeds 99% for particles above 1,000 µm. Leaching experiments have revealed that oxalic acid (OA) and a combination of oxalic acid and EDTA (OAPE) were more efficient than citric acid (CA) and a combination of citric acid and EDTA (CAPE) for the desorption of heavy metals, respectively. The comparison of OAPE and eddy leaching found that the latter improved the desorption efficiency by 9.4%, 7.5%, 7.2% and 7.8% for As, Cd, Sb and Pb compared to the former, respectively. The results demonstrated that the eddy leaching technique could further enhance the desorption efficiency of heavy metals. It is expected to provide technical support for soil remediation with reduced usage of leaching agents. [Display omitted] [ABSTRACT FROM AUTHOR]

A pipe hydrocyclone is easy to disassemble in agricultural machinery. Spiral flow can be generated to drive the movement of impurities in the pipe, thereby effectively reducing the accumulation of impurities. Different structural parameters can form differences in the annular gap space of hydrocyclones. The structure of the annular gap space can also dominate the flow field distribution and swirl efficiency. Therefore, this article aims to explore the annular gap spiral flow formed by the hydrocyclones with different structural parameters using physical model experiments. The research results show that the structural parameters of hydrocyclone were dominated by the magnitude and dispersion of axial, radial and circumferential flow rates, where the most contribution was the radial and circumferential flow rates. There was no change in the overall distribution pattern of the annular gap flow field. Furthermore, there was the roughly same variation trend of axial average velocity and standard deviation along the water flow direction under different structural parameters. Both showed a gradually decreasing trend along the way. However there was a relatively small amplitude of the decrease in the axial average velocity along the way. The standard deviation of the cross-section gradually decreased in the constant diameter of the hydrocyclone, as the length increased, whereas, the axial average velocity increased. However, there were relatively small changes in the standard deviation and axial average velocity. Both axial average flow velocity and standard deviation increased in the constant length of the hydrocyclone, as the diameter increased, whereas, there was a relatively large variation in their amplitude. The radial average velocity and standard deviation showed a "V" shaped trend of decreasing first and then increasing along the flow under different structural parameters. The radial average velocity and flow velocity fluctuation of each section gradually increased in the constant diameter of hydrocyclone, as the length increased, but the increase was relatively small. The radial average velocity decreased in the constant length of hydrocyclone, as the diameter increased, but the flow velocity fluctuation of each section increased gradually. The circumferential average velocity and standard deviation of different structural parameters showed a gradually increasing trend along the water flow, but their growth rate in the first half of the annular gap was relatively small. The circumferential average velocity and flow velocity fluctuation showed a gradually increasing trend in the constant diameter of hydrocyclone, as the length increased, but the increased amplitude of both was relatively small. The circumferential average velocity and flow velocity fluctuation showed a gradually increasing trend in the constant length of hydrocyclone, as the diameter increased. Both energy consumption and rotation efficiency increased significantly, as the length or diameter of hydrocyclone increased. In addition, there was a higher increase rate with the diameter than that with the length. This experiment demonstrated that the hydrocyclone with a structural parameter of 70 mm×100 mm presented the highest starting efficiency. The optimal structural parameter of hydrocyclone was in the size of 70 mm×100 mm. This finding can provide a strong theoretical basis and reference for the selection and structural optimization of the hydrocyclone. [ABSTRACT FROM AUTHOR]

An attempt has been made to develop a non-intrusive and robust technique for online process monitoring of hydrocyclones using commercially available vibration sensors. Vibration signals were captured first at the spigots of 50.8 mm and 76.2 mm diameter hydrocyclones while using water only at different operating conditions. For denoising the captured raw vibration signals, a wavelet-based method coupled with median filtering-based technique was used. The Root Mean Square (RMS) values of vibration accelerations induced in the hydrocyclone were found to be proportional to the total volumetric feed rate. Based on this observation, it has been demonstrated how suitable empirical correlations can be developed which can ultimately be used as an online process monitoring tool for hydrocyclones. [ABSTRACT FROM AUTHOR]

The real media encountered in oil and gas production are usually dispersed, i.e., they are systems consisting of at least two phases, with one of the phases being distributed into the other. Production, collection and transportation of oil and gas are based on multiphase technology, including the processes of lifting from the reservoir, transportation to separation points, separation and infield transport of multiphase mixtures, which consist of oil, gas, formation water and mechanical impurities. In most technological processes of oil and gas production and transport of hydrocarbons, the separation of dispersed systems is necessary. In practice, the unsuitability of hydrocyclone technology for separating emulsions has been established, although hydrocyclones are effectively used for cleaning suspensions, for separating solid particles from liquids, for example, for cleaning drilling fluids from sludge. Recent studies have established that cylindrical multiphase flows are based on the interaction of continuous and dispersed phases, the driving force of which is an additional shear force directed towards the flow axis. In the paper, according to the multiphase technology, the reason for the low efficiency of hydrocyclones for multiphase disperse systems was analyzed. The condition of equality of the shear and centrifugal forces during the operation of the hydrocyclone is shown. It has been established that, based on the correct choice of technological parameters, it is possible to avoid the negative effect of the shear force in cylindrical flows on the operation of hydrocyclones. [ABSTRACT FROM AUTHOR]

This study introduced Krebs hydrocyclone into fine coal EGS process, examined the ultrafine classification effect of Krebs hydrocyclone by single-factor tests and orthogonal tests, and evaluated the fine coal EGS effect after ultrafine classification. Besides, the flow field characteristics in Krebs hydrocyclone were explored by simulation. The optimal grading efficiency of the verification test is 91.32%, and the content of ultrafine particles can be reduced to 1.01%, which prove the excellent ultrafine classification effect of Krebs hydrocyclone. The optimal combustible recovery and ash removal rate are 94.29% and 98.52%, respectively, and when the clean coal ash drops below 10%, the combustible recovery is more than 80%, which reveal that the sorting indexes of fine coal EGS after ultrafine classification are much better than that of unclassified coal. Both the static pressure and velocity in Krebs hydrocyclone have good symmetry and certain regularity. Due to the use of water as a separation medium, the introduction of Krebs hydrocyclone in the fine coal EGS process provides an effective and prospective approach for the industrial application of enhanced gravity separators in the fine coal washing process, especially in the face of increasingly serious environmental problems. [ABSTRACT FROM AUTHOR]

Efficient enrichment of macerals improves the liquefaction efficiency of low-rank coal. The paper studied the characteristics of Shendong low-rank coal, including proximate and ultimate analyses, size and density compositions, and petrographic analysis, as well as the migration regularity of narrow particle size of low-rank coal macerals in the enhanced gravity field. On this basis, a novel classification separation process for low-rank coal macerals using Krebs hydrocyclone and enhanced gravity separator was proposed. The classification size was determined to be 0.074 mm and Krebs hydrocyclone achieved a satisfactory classification effect with a classification efficiency of 84.72%. Based on the enhanced gravity separation results of macerals from hydrocyclone underflow and overflow, the optimal sorting solutions for underflow and overflow were obtained through response surface analysis, respectively. Through the novel classification separation process, the vitrinite content of clean coal has been increased from 46.60% to 61.33% with an outstanding recovery of 77.40%. The novel classification separation process using hydrocyclone and enhanced gravity separator develops an excellent enrichment effect for low-rank coal macerals, which also provides a prospective approach for the cleaner utilization of low-rank coal. [ABSTRACT FROM AUTHOR]

The Seridó region, located in northeastern Brazil, in the states of Paraíba and Rio Grande do Norte, is known for its vast reserves of kaolin from pegmatites. Small companies mine and process ore. However, these operations are precarious, lacking mining planning and processing studies. Consequently, the recovery rates are only 25%, and mining accidents happen. Within a Ministry of Science and Technology work project named Associated Entities, the Centre for Mineral Technology and the Federal University of Campina Grande carried out integrated research, technology and innovation actions to add value to the mineral production chain in the Seridó region. After elaborating on a working plan, the partners collected information on the area, which they used to construct geological maps and computerized mine models. In addition, a kaolin processing plant with a hydrocyclone, aiming to increase the ore's recovery, was studied. This project results were two pit design scenarios with distinct geometric characteristics for the mine planning stage. The first scenario presented better results than the second, with a higher ore tonnage recovery and a lower waste/ore ratio. In the processing stage, the hydrocyclone tested plant led to a concentrate with high kaolinite percentages. The mining and processing project showed the possibility of extracting and processing the kaolin ore in a safer and more economically viable way for small producers. [ABSTRACT FROM AUTHOR]

The problem of judicious selection of hydrocyclone design parameters to minimize energy consumption while ensuring the required suspension separation indicators with a prescribed volume output was studied. Theoretical analysis showed that energy consumption would be minimal if the inlet pipe diameter is 0.366 part of the diameter of the cylindrical part of the hydrocyclone and the diameter of the top drain-pipe, which can be determined by an equation depending on the angle of the tapering part of the hydrocyclone and on the ratio of the diameter of the separation boundary grain to the diameter of the tapering part of the hydrocyclone. The dispersed phase to dispersion medium density ratio does not affect energy consumption. [ABSTRACT FROM AUTHOR]

Hydrocyclone is the basic application equipment of purification treatment in the process of oil and gas field exploitation. With the continuous development of the oil field, the actual exploitation environment of the oil field is getting worse and worse, and the requirements for the equipment treatment efficiency of hydrocyclone are getting higher and higher. In order to improve the treatment efficiency of hydrocyclones and meet the actual treatment requirements, several main hydrocyclones in oil field purification treatment were introduced, and their separation principles and research progress were analyzed and summarized in detail. According to the different types of hydrocyclones introduced, a systematic summary and prospect were made, and the research direction of hydrocyclones in the future was pointed out. [ABSTRACT FROM AUTHOR]

An attempt has been made in this work to experimentally investigate the water split behavior of hydrocyclones for extracting the relevant features that are characteristic of hydrocyclone design conditions only. The experimental findings demonstrated that at high feed flowrates, the water split of the hydrocyclone attains a consistent value, referred to here as the stable split value, because of a fully developed and steady vortical flow through the hydrocyclone. These stable split values were shown to be characteristic of the hydrocyclone design conditions. An empirical model developed in the study considering the key hydrocyclone design variables could predict the stable split values with a validation R2 of 0.98 and 0.96 for the training and testing data, respectively. It is believed that such a design-dependent parametric representation of the water split behavior can be significantly useful for hydrocyclone design comparison and selection which has not been reported in the literature so far. [ABSTRACT FROM AUTHOR]

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 0.26D 2 to 0.56D 2 , 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. [Display omitted] • The accuracy of the mathematical model used in the paper was verified. • Effects of the vortex finder diameter on the classification performance were studied. • Effects of the vortex finder depth on the separation performance were studied. • Separation efficiency of the hydrocyclone was analyzed. [ABSTRACT FROM AUTHOR]

This study aimed to develop a hydrocyclone with a spiral guide feeding body structure to improve classification efficiency and classification accuracy. The spiral guide feeding body structure could pre-arrange the particles before they entered into the separation chamber, thus avoiding the turbulence of the flow field and effectively improving the separation efficiency and separation accuracy. The flow field features and separation performance of a hydrocyclone were studied using the response surface method to obtain the prediction model of separation efficiency and cut-size and the interaction law between influencing factors and the optimal combination of parameters under multiple response indicators. The industrial application showed that the classification efficiency was improved by 4.56% over the conventional feeding body structure. This indicated that the hydrocyclone with a spiral guide feeding body structure had potential industrial application value and certain advantages in improving the separation performance. [ABSTRACT FROM AUTHOR]

Abstract 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. [ABSTRACT FROM AUTHOR]

This study demonstrates the use of hydrocyclone as a thickener to precipitate sulfate ions from wastewater. Simulated wastewater containing different concentrations of sodium sulfate (100–400 mg L−1) dissolved in distilled water was prepared. Lime was added as the precipitating agent. Different flow rates of the feed (3–11 L min−1) were used for two split ratios (0.1, 0.9). The results showed that increasing inlet flow rate, initial concentration, and split ratio enhanced the separation by concentrating sulfate ions in the underflow. Design Of Experiments was performed to determine the most effective factor on the response (underflow concentration) and to assign the optimum operating conditions. The effect was in the order: inlet flow rate, initial concentration, and split ratio. The quadratics of the factors also affected the separation in the order (inlet flow rate)2, (inlet flow rate) × (split ratio), (inlet flow rate) × (initial concentration). The optimum (maximum) value of the underflow concentration of sulfate ions was 856.538 mg L−1 at the optimum operating conditions (11 L min−1 inlet flow rate, 400 mg L−1 initial concentration, and 0.9 split ratio). The experimental value at the optimum operating conditions was 932 mg L−1 including 8% error. The process was applied on a real wastewater taken from a tile factory. The results confirmed the experimental results in that the pollutant was concentrated in the underflow. It was concluded that using hydrocyclone as a thickener was feasible to separate sulfate ions from wastewater. Also, the separation using hydrocyclone could be integrated with another technique such as electrocoagulation or ion exchange to recover sulfur as an attempt toward sustainable development requisites. [ABSTRACT FROM AUTHOR]

Taper angle is an important factor for characterizing a hyrocyclone's separation performance. Appropriate setting of the taper angle can contribute to particle grading and separation performance of the hydrocyclone. Through numerical analysis, this study investigated the flow fields and separation performances of the hydrocyclones with different taper angles in depth. Moreover, the numerical simulation results were compared with experimental data of the conventional hydrocyclone for accuracy validation. The results showed that the tangential velocity, axial velocity, and the diameter of air core increased with the increasing taper angle. At a too large or a too small taper angle, the inner flow field would become unstable, thereby leading to the increasing number of dislocated particles and reducing the particle separation precision. For the hydrocyclone with a diameter of 75 mm, the separation precision of fine particles can be remarkably enhanced by setting the taper angle of 15°, accompanied with the improvement of product quality. The present data can provide the related enterprises with favorable guidance and a theoretical foundation for further designing the taper angle of novel hydrocyclones. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

There are many factors that affect the separation performance of the hydrocyclone, including the structure of the feed body, but the mechanism of influence of the internal flow field of the hydrocyclone on the Axial Velocity Wave Zone (AVWZ) is not yet clear. Based on the numerical test method, this paper analyzes the influence of the feed body structure on the internal flow field and the particle distribution characteristics of the AVWZ and its internal relationship with its separation performance. The results show that the influence mechanism of the structural parameters of the inlet structure on its separation performance is extremely complex, but all of them are reflected in the AVWZ's characteristics, including the flow field characteristics, spatial distribution characteristics, and internal particle distribution. The changes on the inlet diameter will also influence the flow field, centrifugal strength, turbulence strength, and particle distribution, while the inlet aspect ratio is altered largely by changing the settling distance of particles. Finally, effects of inlet structure on the separation performance of the hydrocyclone can be explained from the AVWZ, which provides the basis for designing the inlet structure to improve separation performance. [ABSTRACT FROM AUTHOR]

Inlet head, as the multi-phase flow transport channel, imposes significant effects on the separation performance of a hydrocyclone. Ultra-fine powder is an inevitable product in the mining processing industry and sets extremely high requirements on product quality. Because of favorable water-carrying capability, fine particles can be hardly separated in a conventional feeding body. In order to satisfy the separation requirements of fine particles, this study designed a vorticose involute-line diversion inlet head that can effectively enhance the separation precision of fine particles and improve the product quality. Meanwhile, this study selected four hydrocyclones with different feeding structures for comparative analysis, and explored the isobaric pressure, velocity field, air core, and separation performance of the hydrocyclones through numerical simulation. The numerical analysis results showed that the effective pressure range in the novel hydrocyclone expands and the energy loss drops. The air core diameter is the lowest, the separation space of fine particles is the greatest, and the separation time is the longest, which can achieve a more thorough separation with the highest cutting capability and separation precision of fine particles. Finally, after an optimum design, the separation performance achieves the optimal at a wrap angle of 180°. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A rectangular inlet generally exceeds a circular inlet in separation performance. However, there still lacks detailed information that can appropriately determine the height-to-width ratio of the rectangular inlet. For this reason, this study investigated the effect of the height-to-width ratio of the rectangular inlet on the separation performance of hydrocyclone with a diameter of 75 mm through numerical analysis. The numerical results fitted well with the experimental data and thus validated the effectiveness of the present method. The appropriate height-to-width ratio was determined by overall analyzing the pressure field, the velocity field, the air column, the turbulence field in the hydrocyclone and the separation efficiency. Based on the present research results, as the height-to-width ratio increased, both the pressure drop and tangential velocity first increased and then decreased, while the turbulence energy first decreased and then increased. At a height-to-width ratio of 3, the short-circuit flow rate and the turbulence energy were lowest and the separation precision was highest, suggesting favorable product quality. Conclusively, for the hydrocyclone with a diameter of 75 mm, the optimal height-to-width ratio of the rectangular inlet should be within the range of 3~4. This finding can provide insightful foundation for designing a reasonable inlet. [ABSTRACT FROM AUTHOR]

Solid phase is an important component of drilling fluid, but when drilling fluid with high solid content is injected to well bottom, it leads to decrease in rate of penetration (ROP) and waste of drilling energy. Therefore, it is an economic method to add solid control equipment near bit to achieve solid removal of bottom-hole drilling fluid. Based on hydrocyclone separation technology, this paper presents a new near-bit hydrocyclone (NBHC) installed with guide vanes for downhole solid–liquid separation. Structure and separation mechanism of NBHC are introduced. This tool can separate part of solids contained in drilling fluid into wellbore annulus in advance, especially plugging particles. In this way, the solid content of drilling fluid flowing into bit will reduce, thereby the bit rock-breaking environment will improve and ROP increase. Firstly, the Euler multiphase flow model is adopted to simulate the NBHC for Φ311.2 mm wellbore. The results indicate that NBHC has a strong ability of drilling fluid solid separation, and the mass separation efficiency reaches 79.30%. Then, the effects of nozzles diameter, mud flow rate, solid volume fraction and solid size on the separation efficiency and pressure drop of NBHC are studied by simulation. Results show that the separation efficiency is positively correlated with nozzles diameter and solid size, negatively correlated with solid volume fraction, but not significantly correlated with inlet mass flow rate. It is proved that appropriate structural parameters help to further improve the working performance of NBHC, and it is an effective way to increase the ROP indirectly. [ABSTRACT FROM AUTHOR]

The monodisperse pseudo-boehmite (PB) is an essential raw material for the preparation of the hydrogenation catalyst carrier, γ-Al 2 O 3 , which is of great significance for the efficient conversion of heavy crude oil and the development of the residue hydrotreating technology. The introduction of hydrocyclone has been proved to better improve the grade efficiency of PB particles. However, in the actual production process, it is found that the change of slurry viscosity will have a serious impact on particle size control and centrifugal classification of PB particles. Therefore, in this paper, based on the computational fluid dynamics (CFD), the internal flow field characteristics of the hydrocyclone and the effect of continuous phase viscosity on particle classification efficiency were systematically studied. The results demonstrated that hydrocyclone not only participated in particles classification, but also indirectly promoted particle growth. Satisfied classification efficiency was obtained in practical industrial applications by adopting the optimized condition parameter (Na 2 CO 3 concentration of slurry 5 wt%). The average PB particles size increased from 12.9 µm to 40.3 µm, and the corresponding separation efficiency was improved to 74.9%. The obtained results can provide a feasible reference and theoretical basis for optimization of continuous-carbonization preparation process of PB particles. [Display omitted] • The effect of slurry viscosity on PB centrifugal classification was numerically simulated. • Efficient classification and rapid growth of PB particles were achieved in hydrocyclone. • The average PB particles size was increased to 40.3 µm by slurry viscosity control. • The separation efficiency of PB particles was improved to 74.9% in the industrial pilot test. • Fish-hood effect of PB particles classification in hydrocyclone was discussed. [ABSTRACT FROM AUTHOR]

An industrial water injection hydrocyclone was adopted in the Taixi coal preparation plant to overcome the shortcoming of fine particle entrainment in the underflow and improve the grading efficiency. Parameter optimization of the hydrocyclone was critical prior to putting it into production. A particle swarm optimization optimized support vector machine (PSO-SVM) model based on uniformly designed experiments was built. It was satisfactory in accuracy as the average of the absolute of relative error was 1.73% for the training dataset, and the relative error of the test dataset was 8.43%. The trends of grading efficiency versus underflow port diameter, inlet pressure and water injection pressure were analyzed, respectively. It was found that the maximum efficiency was obtained when underflow port diameter was 50 mm, inlet pressure was 0.25MPa and water injection pressure was 0.04 MPa. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

• Health state assessment and remaining useful life prognostic of hydrocyclone • Augmenting degradation sequences by fusing mechanism modeling and TimeGAN learning • A unified framework for constructing and clustering degradation health indicators • Quantifying prediction uncertainty of remaining useful life of equipment Deploying health state (HS) assessment and remaining useful life (RUL) prognostic on the industrial equipment can effectively avoid shutdown and reduce productivity losses. This paper proposes a temporal self-clustering (TSC) and time-series generative adversarial network (TimeGAN) based uncertainty-aware health prognostic algorithm for the hydrocyclone, a critical machine in the mineral processing. To label the HS of degradation data, an autoencoder based TSC algorithm is proposed. It integrates the extraction and clustering of health indicators into a unified framework, so that the correlation information between feature extraction and clustering can be captured for cluster analysis. A Benders decomposition based optimization approach is designed to synthetically optimize network weights and clustering centers, thereby extracting and labeling data features more reasonably. For quantifying prediction uncertainty, an uncertainty-aware prognostic algorithm is proposed to predict the RUL distribution, and the uncertainty can be quantified as the standard deviation (Std) of the distribution. Furthermore, a mechanism and TimeGAN fusion temporal sequence generation algorithm is proposed to augment the degradation process sequences of the equipment. Verification experiments using the actual data show that the proposed algorithm can effectively evaluate the HS of the equipment and provide a sensible and convincing RUL prediction. [ABSTRACT FROM AUTHOR]

Accelerating the prediction time of separation performance and flow field characteristics in industrial hydrocyclones holds paramount importance for real-time control. Machine learning methods exhibit significant advantages in this particular aspect. This study presents a network model that integrates a long short-term memory (LSTM) layer with a fully connected layer to accurately forecast the flow field and separation performance under various operational conditions, leveraging CFD data. The study evaluates the effect of factors such as the number of LSTM layers and neurons per layer on the model's performance, aiming to identify the optimal network structure. The results demonstrate that the predicted flow field and performance of the hydrocyclones using LSTM closely align with the outcomes from CFD simulations. The average absolute percentage error is constrained to within 6%, which significantly enhances the prediction efficiency. The findings contribute to a more efficient and automated separation process in industrial environments. [Display omitted] • The inner flow behaviors can be instantaneously predicted by the derived LSTM. • The layers and neurons are investigated to achieve optimal parameters in LSTM. • The proposed model has an average absolute percentage error within 6%. • The derived LSTM saves huge computational time compared to CFD model. [ABSTRACT FROM AUTHOR]

[Display omitted] • Effects of particle size distribution are experimentally and numerically revealed. • Physical tests show non-monotonic variations in the cut size and curve slope. • The d 50f and σ J have opposite effects on P and R f with one factor held constant. • The interplay between the two factors on d 50c and cut sharpness is intricate. • Classification is controlled by the flow field and relative sizes of d 50c and d 50f. Classification by particle size using hydrocyclones is a fundamental step in various industries, yet the influence of material properties remains an area of limited understanding. This paper presents a comprehensive experimental and numerical investigation to illuminate the complex relationship between the feed particle size distribution (PSD) and the classification process. The feed PSD is characterised by two crucial parameters: the median size (d 50f) and the distribution coefficient (σ J), derived from Johnson's SB function. The results reveal non-monotonic variations in cut size and curve slope during physical tests where the two parameters are not separated. With one parameter held constant in numerical tests, an increase in d 50f generally leads to a decrease in pressure drop but an increase in water split, while σ J exhibits an opposite trend. The interplay between the two parameters and their effects on cut size and cut sharpness is intricate, primarily determined by the characteristics of the flow field and the relative sizes of the cut size and d 50f in the feed. These findings underscore the critical role of feed material properties in operating hydrocyclones for fine particle classification. [ABSTRACT FROM AUTHOR]

• Numerical simulation was used to study the effect of surface hydrophobic of fine particles on hydrocyclone separation. • Increasing the contact angle of the particles can effectively reduce drag force and greatly improve the separation efficiency. • The total separation efficiency increased from 69.6 % to 76.71 %, and the cut size decreased from 22.4 μm to 17.8 μm. Hydrocyclones are devices that can efficiently separate and classify mixtures of multiphase systems based on density and grain size differences under centrifugal sedimentation. The cut size, denoted as d 50 , indicates the separation performance of the device, with lower values indicating higher separation limits. To reduce the cut size, researchers have tried different methods, such as modifying the hydrocyclone structure or increasing the feed pressure. However, the contact angle of the fine particles has a significant effect on their drag force, which affects the separation efficiency and accuracy. In this study, we explored the effect of surface wettability on the separation process and proposed an interface regulation method to reduce the cut size. Our experimental results indicate that by changing the contact angle from 10° to 87°, the total separation efficiency of hydrophobic glass beads increased from 69.6 % to 76.71 %, and the cut size decreased from 22.4 μm to 17.8 μm under the same operating parameters. Our work is of great theoretical interest and potential engineering applications for improving the efficiency and accuracy of hydrocyclone separation of fine particles. [ABSTRACT FROM AUTHOR]

The performance of multiphase flow processes is often determined by the distribution of phases inside the equipment. However, controllers in the field are typically implemented based on flow variables, which are simpler to measure, but indirectly connected to performance (e.g., pressure). Tomography has been used in the study of the distribution of phases of multiphase flows for decades, but only recently, the temporal resolution of the technique was sufficient for real-time reconstructions of the flow. Due to the strong connection between the performance and distribution of phases, it is expected that the introduction of tomography to the real-time control of multiphase flows will lead to substantial improvements in the system performance in relation to the current controllers in the field. This paper uses a gas–liquid inline swirl separator to analyze the possibilities and limitations of tomography-based real-time control of multiphase flow processes. Experiments were performed in the separator using a wire-mesh sensor (WMS) and a high-speed camera to show that multiphase flows have two components in their dynamics: one intrinsic to its nonlinear physics, occurring independent of external process disturbances, and one due to process disturbances (e.g., changes in the flow rates of the installation). Moreover, it is shown that the intrinsic dynamics propagate from upstream to inside the separator and can be used in predictive and feedforward control strategies. In addition to the WMS experiments, a proportional–integral feedback controller based on electrical resistance tomography (ERT) was implemented in the separator, with successful results in relation to the control of the distribution of phases and impact on the performance of the process: the capture of gas was increased from 76% to 93% of the total gas with the tomography-based controller. The results obtained with the inline swirl separator are extended in the perspective of the tomography-based control of quasi-1D multiphase flows. [ABSTRACT FROM AUTHOR]

Tapered segment, the main separation region in a hydrocyclone, is mainly used to cut off the short-circuit flow. Generally, a single straight-line tapered segment is set in a conventional hydrocyclone, the effects of multi-curved-line combination-type tapered segment on the flow field in the hydrocyclone and the related separation performance have been poorly investigated. In this study, five different types of hydrocyclones with different tapered-segment structures (straight line, parabolic curve, hyperbolic curve, the combination of parabolic curve and straight line and the combination of hyperbolic curve and straight line), denoted as Type A, Type B, Type C, Type D and Type E hydrocyclones, respectively) were selected for numerical analysis. The simulation data were compared with classical experimental values by Hsieh et al. to validate the accuracy. Moreover, the changes of pressure fields, velocity fields, air columns, turbulence intensities and separation efficiencies in five different hydrocyclones were investigated in depth. The results showed that both the pressure drop and the tangential velocities of Type C and Type E hydrocyclones were higher than that of Type A hydrocyclone, while the pressure drop of Type B and Type D hydrocyclones was lower than that of Type A hydrocyclone. Under a higher pressure, fine particles moved toward the center more easily, thereby leading to the decreasing number of dislocated particles. Compared with conventional straight-line tapered segment, the combination-type tapered segment exhibited smaller axial velocity, which prolonged the retention time of particles in the hydrocyclone and contributed to full particle separation. The turbulence intensity can be weakened by changing the tapered-segment structure. The turbulence intensity in Type D hydrocyclone was lowest among the five hydrocyclones. In addition, the separation performance of hydrocyclones can also be enhanced by changing the structural form of the tapered segment. Type B hydrocyclone was featured by favorable separation performance and Type D hydrocyclone exhibited a small cutting size. [ABSTRACT FROM AUTHOR]

The process of the separation of inhomogeneous systems is considered for the case in which the density of particles of the dispersed phase is less than the density of the dispersion medium. It is proposed to carry out the process in a hydrocyclone with a drain-pipe filtering surface under vibration, which ensures vibroliquefaction of the formed sludge and continuous regeneration of the pores of the filter partition. An algorithm is presented, and an example of numerical calculation of the hydrocyclone process of "light" fractions of the dispersed phase with additional purification on the drain-pipe filtering surface is given in comparison with a typical apparatus. [ABSTRACT FROM AUTHOR]

The double vortex-finder hydrocyclone formed by a coaxial insertion of an internal vortex-finder with a smaller diameter inside the conventional single vortex-finder used to obtain two kinds of products from the internal and external overflows in one classification has attracted wide attention. To further improve the classification performance of the hydrocyclone, the effects of the internal vortex-finder diameter and length on the classification performance were studied by numerical simulation and response surface modeling with the behavior of fluid and particle motion in the double vortex-finder hydrocyclone as the research object. The results showed that the split ratio and pressure drop of internal and external overflow increased with the diameter of the internal vortex-finder. The classification performance was optimal when the diameter ratio of internal and external overflow was 0.88, the yield of −20 μm particles was more than 80.0%, and the highest was 95.0%. Increasing the internal vortex-finder length could reduce the coarse particle content and improve the classification accuracy of the internal overflow product. When the length of the internal vortex-finder is larger than 80 mm, the +30 μm yield was lower than 20.0%, and the maximum k value was 16.3%; the k is the significant factor used to characterize the effectiveness of −20 μm particle collection. The response surface modeling revealed that the internal vortex-finder diameter was the most important factor affecting the distribution rate of internal overflow. This paper is expected to advance the development of the classification industry. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cone angle had great influence on plastic separation. • The recovery of particles with wide size distribution was studied. • The discrepancy of settlements of PET/PVC were significant. • The optimum cone angle and L/D were obtained. The cone angle of a hydrocyclone is believed to be an important parameter to affect the separation performance. For the recycling of waste plastics, this paper focused on the study of the influence of cone angles on the separation of light dispersed plastics (PET) and heavy dispersed plastics (PVC) by experiments and numerical simulations. The cone angle was changed from 3° to 28° either at given length of the cylindrical section or at fixed total length of the hydrocyclone. The separation performance varied with cone angles at given length of the cylindrical section more greatly than that at fixed total length of the hydrocyclone. Results show that particles with different sizes in mixture exhibited discrepant separation behaviors at various cone angles. There was an optimum cone angle at which the Newton efficiency peaked as 90.2%, while the purity of PET could also reach the highest. The proportion of cylindrical section could be properly small for the enhancement of Newton efficiency. [ABSTRACT FROM AUTHOR]

De-oiling hydrocyclones are extensively applied in oilfield wastewater purification for fluid separation, because of their efficient and rapid processing performance. However, it is difficult for a hydrocyclone to separate tiny oil droplets owing to the inadequate centrifugal force. A type of coalescence hydrocyclone (CHC) is designed based on the principle of centrifugal separation and hydraulic droplet collision coalescence. The structure, coalescence theory, and separation principle of the CHC are introduced. Based on the Euler–Euler method, the population balance model (PBM) is applied to a continuous equation to simulate the distributions of the velocities, oil volume fraction, and oil droplet size in the CHC. The simulation method is verified by conducting particle image velocimetry tests in a polymethyl methacrylate hydrocyclone. The results indicate that the CHC can improve the separation performance by enlarging the oil droplet size by collision coalescence before entering the hydrocyclone. The results of separation efficiency experiment indicate that the CHC can not only improve the oil–water separation efficiency but also clearly enhance the processing capability. The optimal inlet flow rate is 5.5 m3·h-1 and the split ratio is 25%. The feasibility of the structure design and the reliability of the separation performance are validated by experiments. [ABSTRACT FROM AUTHOR]

The efficiency of grinding and flotation process in copper-molybdenum processing circuit, largely affected by performance of thickeners and hydrocyclones devices. The goal of this paper is to investigate the effect of the rate-limiting factors on the performance of these devices and consequently on grinding and separation efficiency of the molybdenum processing circuit. So, a full process mineralogical study have been carried out on outputs of thickeners and hydrocyclone of the molybdenite flotation circuit. According to the results, coarse-grained fractions (>50 μm) of the planar molybdenite will not necessarily be recovered by thickener and hydrocyclones. This is especially true for hydrocyclones when the inlet-load rate is high, i.e., the erroneous discharge of planar molybdenite particles from the overflow of hydrocyclone, as well as their floatability in the thickener overflow, can be attributed to the effect of particle shape and size. This issue harms the grade and recovery of flotation due to the increase in the amount of circulating load (regrinding) and consequently the generation of fine particles (<10 μm) in the hydrocyclone-milling circuit. On the other hand, the almost spherical particles of copper minerals, as well as the nonplanar molybdenite fine-grained particles, are easily removed from the hydrocyclone underflow or settled in thickeners. The introduction of copper mineral particles into molybdenum concentrate and vice versa has reduced the quality of the produced concentrate and undesirable flotation performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Filtering Conical Hydrocyclones shows lower energy consumption than conventional. • A filtering hydrocyclone was optimized for split ratio while kept low Euler Number. • The optimized geometric relations were: Di/Dc = 0.29, Do/Dc = 0.35, L/Dc = 4.7, θ = 20°. • The optimized configuration (FCoH-OTS) reduced the split ratio by up to 28.6%. • The optimized configuration (FCoH-OTS) reduced the Euler number by up to 49.5%. The growing demand for process improvement and cost reduction has motivated many studies involving modifications in conventional devices. The filtering hydrocyclone is a non-conventional hydrocyclone that combines filtration with centrifugal separation to reduce energy costs and increase separation efficiency. In the present work, an optimization study was developed using Differential Evolution (DE) algorithm to obtain a filtering conical hydrocyclone (FCoH) categorized for thickening purposes (minimum split ratio) with low energy consumption (low Euler number). A performance comparison showed that FCoHs had an Euler number that was up to 40% lower than those found in the conventional hydrocyclones of the same geometry. The filtering hydrocyclone geometry obtained in the optimization study, named FCoH-OTS, resulted in the lowest split ratio (S = 9.59%) and Euler number (Eu = 665) among the 25 different configurations investigated in this research. The optimized configuration led to reductions of 28.6% in the split ratio and 49.5% in the Euler number compared to the hydrocyclone from the experimental design with the lowest split ratio. The low values obtained for the split ratio and Euler number confirmed the expectation of a hydrocyclone for thickening purposes with low energy consumption. [ABSTRACT FROM AUTHOR]

It is shown by computer modeling that at feed pipe and top drain pipe diameters to cylindrical hydrocyclone body part diameter ratio of 0.41 hydraulic losses are minimized if volume flow rates of the suspension separated in the hydrocyclones are equal. Hydrocyclone designing with appropriate ratios of the geometric parameters makes it possible to reduce their overall dimensions without decrease of the prescribed separation factors and volume throughput, but with some increase of power consumption. Equations are derived for calculating volume throughput and separation boundary grain of hydrocyclones with geometric and operating parameters varying in a wide range. [ABSTRACT FROM AUTHOR]

Isobaric surface is a characteristic feature generated during particle motion in the hydrocyclone. Its pattern and position can directly affect the separation performance, which has rarely been studied. In this study, the isobaric surface and flow field in the hydrocyclone with different apex/vortex ratios were investigated in-depth via numerical analysis, and the effects of air core on axial velocity and tangential velocity were explored. On that basis, the effect of apex/vortex ratio on the hydrocyclone's separation performance was analyzed. The results showed that both pressure and tangential velocity increased with the increasing apex/vortex ratio. Through theoretical study and numerical analysis, the isobaric surface in the forced- and free-vortexes showed parabolic and hyperbolic patterns, respectively. As the apex/vortex ratio increased, the isobaric surface moved towards the center of hydrocyclone, suggesting the expansion of free-vortex region, the shrinkage of the forced-vortex region, and thus the failure in particle gradation and separation. Air core can lead to the fluctuation of both axial and tangential velocities. The fluctuation frequentness increased with the apex/vortex ratio, causing the disorder of flow field and the reduction of separation efficiency. At an apex/vortex ratio of 3/2, fluid can only move downwards and the hydrocyclone no longer played the role of gradation. As the apex/vortex ratio increased, the content of fine particles in the underflow increased drastically, and most of coarse particles were discharged from the underflow port. In contrary, the cutting capability and separation precision increased with the decline of the apex/vortex ratio. Therefore, in order to obtain high-quality product, the apex/vortex ratio should be as small as possible under the premise of satisfying the separation requirement. [Display omitted] • The effect of isobaric surface on separation performance was studied. • The accuracy of the model used in the numerical simulation was verified. • The effect of air core on velocity field was studied. • The small apex/ vortex ratio possessed better product quality. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel Hydrocyclone with circular rings introduced • CFD simulations with LES-WALE turbulence model was established to provide accurate predictions • Extensive CFD simulations done to predict performance improvements in novel hydrocylone • Attractive reductions in the bypass of fines and sharper classification observed • Number, location, size, orientation can be optimization variables for further improvements Hydrocylones offer a process intensified environment for rapid, high-throughput and relatively sharp particle classification or phase separation. One of the main performance limitations of hydrocyclone is bypassing of fines to the underflow. To address this limitation, a novel design modification of fitting thin concentric rings to the cylindro-conical section has been proposed. The Computational Fluid Dynamics (CFD) modeling based methodology has been adopted to validate the hypothesis. Predictions using Realizable k - ε , Reynolds Stress Model (RSM), and Large Eddy Simulation Wall Adopting Local Eddy viscosity (LES-WALE) turbulence models has revealed that LES-WALE matched better with the experimental observations. The experimental data included overall performance parameters and detailed observations of axial and tangential velocity profiles across the hydrocyclone. The validated CFD model and the methodology was then used to predict the behavior of the proposed designs. They established that the modifications held promise in reducing the bypass with additional benefits of sharper separation curve and finer D 50. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • Cone angle and its combination sequence have great influence on IOT classification. • As the lower cone angle increases, the classification efficiency increases. • The upper cone angle primarily governs the centrifugal intensity and cut sharpness. • The lower cone angle exerts a greater impact on cut size and water split. • The centrifugal intensity and turbulence intensity determine classification performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • An axial-flow hydrocyclone achieve in-situ desorption of catalyst attachment. • Catalyst self-rotation and coupled centrifugal force models were analyzed. • Self-rotation and revolution speeds are affected by flow rate and insertion depth. • Increasing flow rate and insertion depth enhance the oil phase centrifugal force. • The oil phase is subjected to a periodically varying coupled centrifugal force. As a renewable and environmentally friendly resource, biomass energy has been widely used and is considered to be a promising alternative to petroleum-based liquid fuels. At present, the ebullated bed reactor is generally used to upgrade the biomass pyrolysis liquid, but the catalyst is prone to deactivation due to the polycondensation and coking of bio-oil. This paper proposes an ebullated bed with a built-in axial hydrocyclone to achieve in-situ activation of the catalyst. The influences of the vortex finder insertion depth and the inlet flow rate on the particles' revolution and self-rotation were investigated by numerical simulation, high-speed imaging technology and particle image velocimetry (PIV), and the coupling principle of revolution and self-rotation of catalysts was also analyzed. The results show that increasing flow rate and decreasing vortex finder insertion depth will increase the particles' revolution speed, which varies in the range of 18–78 rad/min. The particles' self-rotation speed varies in the range of 240–1200 rad/min. With the increase of flow rate and vortex finder insertion depth, the particles' self-rotation speed increases, the attached oil phase on particle pores and surfaces receives greater centrifugal force, the coupled centrifugal separation factor increases, and the oscillation period of the coupled centrifugal force decreases, which is beneficial to the desorption of the oil phase. The self-rotation, revolution and their coupling principle are beneficial to the removal of pore pollutants in the catalyst. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two numerical models modified with empirical viscosity correlations are employed. • The dynamic and statistical forces exerted on particles are analysed. • The spatial distribution and flow behaviour of different particles are compared. • The underlying reasons for limited separation sharpness are revealed. • Novel insights into the classification process and principle are provided. The axial velocity fluctuation zone (AVFZ) characterizes the fluctuation range of the locus of zero vertical velocity, where the momentum transfer between the medium and solids is critical but has not been well revealed yet. Based on the viscosity-modified mixture and DPM models, this paper numerically investigated particles' motion behaviour, dynamic forces, spatial distribution, and flow characteristics. The results indicate that the particle size mainly influences drag force (F D) and has little effect on pressure gradient (F P) and centrifugal forces (F C), whereas the particle density affects F C / F P without changing F D. Due to the strong turbulence dispersion in the AVFZ, similar magnitudes of F D , F P , and F C cause prolonged residence time, higher accumulation rate, and higher circulation flow rate of near-cut-size particles, resulting in limited separation sharpness. Taking the AVFZ as a 'bridge', novel insights in the classification process along with the effects of main structural and operating parameters are provided. [ABSTRACT FROM AUTHOR]