Research

15 pages, 1746 KiB

Open AccessArticle

Experimental Study on the Separation Performance of an Intermittent Discharge Concentrated Hydrocyclone

by Peikun Liu, Hui Wang, Lanyue Jiang, Yuekan Zhang, Xiaoyu Li, Yulong Zhang and Zishuo Li

Separations 2023, 10(3), 161; https://doi.org/10.3390/separations10030161 - 25 Feb 2023

Viewed by 950

In the pretreatment for the solid–liquid separation of sewage, the traditional hydrocyclone cannot reasonably achieve a high underflow concentration and high separation efficiency at the same time. An intermittent discharge concentrated hydrocyclone was proposed in this paper to solve this problem. In order [...] Read more.

In the pretreatment for the solid–liquid separation of sewage, the traditional hydrocyclone cannot reasonably achieve a high underflow concentration and high separation efficiency at the same time. An intermittent discharge concentrated hydrocyclone was proposed in this paper to solve this problem. In order to determine the specific separation performance of the intermittent discharge concentrated hydrocyclone, this paper studied the influence of the structure parameters and process parameters on its separation performance through experimental testing. The results indicate that increasing the overflow backpressure improves the separation efficiency but reduces the underflow concentration; that increasing the diameter of the overflow pipe and reducing the diameter of the underflow orifice improve the underflow concentration but reduce the separation efficiency; and that a proper increase in the inlet pressure simultaneously increases the separation efficiency and underflow concentration. The parameter combinations of the hydrocyclone were separately optimized for the underflow concentration and total separation efficiency. Full article

(This article belongs to the Special Issue Research on Separation Performance of Separator)

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16 pages, 14612 KiB

Open AccessArticle

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

by Peikun Liu, Wenxiu Fu, Lanyue Jiang, Xinghua Yang, Yuekan Zhang, Xiaoyu Li and Yulong Zhang

Separations 2023, 10(2), 84; https://doi.org/10.3390/separations10020084 - 26 Jan 2023

Cited by 1 | Viewed by 1376

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Research on Separation Performance of Separator)

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14 pages, 12650 KiB

Open AccessArticle

Influence of Feed Rate on the Performance of Hydrocyclone Flow Field

by Yuekan Zhang, Mingyuan Xu, Yaoxu Duan, Xinghua Yang, Junru Yang and Xiangcheng Tang

Separations 2022, 9(11), 349; https://doi.org/10.3390/separations9110349 - 04 Nov 2022

Cited by 1 | Viewed by 1405

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Research on Separation Performance of Separator)

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17 pages, 1361 KiB

Open AccessArticle

A Resolved Simulation Approach to Investigate the Separation Behavior in Solid Bowl Centrifuges Using Material Functions

by Helene Katharina Baust, Simon Hammerich, Hartmut König, Hermann Nirschl and Marco Gleiß

Separations 2022, 9(9), 248; https://doi.org/10.3390/separations9090248 - 06 Sep 2022

Cited by 4 | Viewed by 2030

Abstract

The separation of finely dispersed particles from liquids is a basic operation in mechanical process engineering. On an industrial scale, continuously operating decanter centrifuges are often used, whose separation principle is based on the density difference between the solid and the liquid phase [...] Read more.

The separation of finely dispersed particles from liquids is a basic operation in mechanical process engineering. On an industrial scale, continuously operating decanter centrifuges are often used, whose separation principle is based on the density difference between the solid and the liquid phase due to high g-forces acting on both phases. The design of centrifuges is based on the experience on the individual manufacturer or simplified black box models, which only consider a stationary state. Neither the physical behavior of the separation process nor the sediment formation and its transport is considered. In this work, a computationally-efficient approach is proposed to simulate the separation process in decanter centrifuges. Thereby, the open-source computation software OpenFOAM was used to simulate the multiphase flow within the centrifuge. Sedimentation, consolidation of the sediment, and its transport are described by material functions which are derived from experiments. The interactions between the particles and the fluid are considered by locally defined viscosity functions. This work shows that the simulation method is suitable for describing the solid-liquid separation in a simplified test geometry of a decanter centrifuge. In addition, the influence of the rheological behavior on the flow in the test geometry can be observed for the first time. Full article

(This article belongs to the Special Issue Research on Separation Performance of Separator)

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13 pages, 6033 KiB

Open AccessArticle

Classification Performance of a Novel Hydraulic Classifier Equipped with a W-Shaped Reflector

by Yuekan Zhang, Yaoxu Duan, Lanyue Jiang and Jingzhen Cao

Separations 2022, 9(8), 212; https://doi.org/10.3390/separations9080212 - 10 Aug 2022

Viewed by 2047

Abstract

In the present research, we propose the use of a novel hydraulic classifier equipped with a W-shaped reflector to enhance classification performance. The effects of the structural dimensions of a W-shaped reflector on the flow field of a classifier and its classification performance [...] Read more.

In the present research, we propose the use of a novel hydraulic classifier equipped with a W-shaped reflector to enhance classification performance. The effects of the structural dimensions of a W-shaped reflector on the flow field of a classifier and its classification performance were investigated using numerical simulations and experiments. The results demonstrate that the reflection of the W-shaped reflector results in the return of the feed material back to the classification cavity. After this, the materials are mixed with a rising water flow in order to avoid the settlement of particles. Thus, the particles can stay longer in the classification cavity, facilitating the generation of a suspension bed and effectively improving the classification efficiency and accuracy. Our data indicates that the overall classification efficiency of the classifier embedded with the W-shaped reflector was 11.19% higher than that of a traditional classifier. Our results provide a reference for classifier optimization. Full article

(This article belongs to the Special Issue Research on Separation Performance of Separator)

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11 pages, 2772 KiB

Open AccessArticle

A Novel Centrifugal Filtration Device

by Chia-Cheng Lin and Jung-Ming Wu

Separations 2022, 9(5), 129; https://doi.org/10.3390/separations9050129 - 21 May 2022

Cited by 3 | Viewed by 3475

Abstract

In the proposed centrifugal filtration device, a filter is mounted in the center of the centrifugal chamber. The particles move towards the centrifuge wall away from the filter under centrifugal force, so a filtration cake is unlikely to accumulate here. The working fluid [...] Read more.

In the proposed centrifugal filtration device, a filter is mounted in the center of the centrifugal chamber. The particles move towards the centrifuge wall away from the filter under centrifugal force, so a filtration cake is unlikely to accumulate here. The working fluid is injected continuously, so the feed pressure is higher than the discharge pressure, which compels the light-phase fluid to leave through the filter as filtrate. The filtrate flux rate and the movement of particles in the centrifugal chamber of the proposed filtration device were investigated using different powder particle sizes, concentrations of working fluid, centrifugal chamber rotation speeds, and filters. With a higher centrifugal chamber rotation speed, the centrifugal force acting on the particles in the centrifugal chamber was stronger, and the particles were less likely to adhere to the central filter; hence, a larger amount of filtrate was produced. Full article

(This article belongs to the Special Issue Research on Separation Performance of Separator)

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15 pages, 9311 KiB

Open AccessArticle

Effect of Internal Vortex-Finder on Classification Performance for Double Vortex-Finder Hydrocyclone

by Yuekan Zhang, Jiangbo Ge, Lanyue Jiang, Hui Wang and Yaoxu Duan

Separations 2022, 9(4), 88; https://doi.org/10.3390/separations9040088 - 31 Mar 2022

Cited by 3 | Viewed by 1944

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Research on Separation Performance of Separator)

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18 pages, 4877 KiB

Open AccessFeature PaperArticle

Study on the Desliming Performance of a Novel Hydrocyclone Sand Washer

by Xinghua Yang, Guanghui Yang, Peikun Liu, Xiaoyu Li, Lanyue Jiang and Jiashun Zhang

Separations 2022, 9(3), 74; https://doi.org/10.3390/separations9030074 - 13 Mar 2022

Cited by 5 | Viewed by 2353

Abstract

A novel hydrocyclone sand washer featured by connecting a cylindrical hydrocyclone and a conical-cylindric hydrocyclone in series was developed to improve the poor grading performance in current machine-made sand processing technology. The former hydroycyclone with a flat bottom was designed to enhance the [...] Read more.

A novel hydrocyclone sand washer featured by connecting a cylindrical hydrocyclone and a conical-cylindric hydrocyclone in series was developed to improve the poor grading performance in current machine-made sand processing technology. The former hydroycyclone with a flat bottom was designed to enhance the centrifugal intensity, thereby achieving the pre-grading of fine and coarse particles and ensuring the discharge of most fine mud particles from the overflow pipe. The latter hydrocyclone was designed to achieve the secondary fine separation and therefore reduce the content of fine particles in the underflow product. Firstly, the flow field inside the consecutive hydrocyclones was simulated using an RSM and VOF model. The DPM model was introduced to trace the particle motion trajectory and validate the feasibility of hydrocyclone separation. Then, the experimental study was performed using the control variable method, and the effects of the first-section overflow pipe diameter, the feeding rate, and the mud–sand mixing ratio on the desliming performance were examined. Results show that the content of particles with a diameter of below 75 μm in the second-section underflow drops significantly after the separation in the hydrocyclone sand washer. When the first-section overflow pipe diameter, the feeding rate, and the mud–sand mixing ratio are set to 34 mm, 60 kg/h and 1:1, respectively, the desliming rate of the novel hydrocyclone sand washer can reach 94.31% and the loss rate of quartz sand is only 1.28%. Full article

(This article belongs to the Special Issue Research on Separation Performance of Separator)

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17 pages, 2464 KiB

Open AccessArticle

Effect of Cone-Plate Clarifier Structure Parameters on Flocculation Efficiency

by Yulong Zhang, Peikun Liu, Linjing Xiao, Long Chang, Fangping Yan and Lanyue Jiang

Separations 2022, 9(1), 6; https://doi.org/10.3390/separations9010006 - 24 Dec 2021

Cited by 1 | Viewed by 2094

Abstract

In this study, a coal mine water flocculation system was established. A series of flocculation tests were carried out at different structural parameters (cylinder height, cone-plate insertion depth and cone-plate spacing) to better investigate the effect of the cone-plate clarifier on coal mine [...] Read more.

In this study, a coal mine water flocculation system was established. A series of flocculation tests were carried out at different structural parameters (cylinder height, cone-plate insertion depth and cone-plate spacing) to better investigate the effect of the cone-plate clarifier on coal mine water treatment performance. Sixteen sampling points were set up in the system for data monitoring to generate the required data. The cone-plate clarifier was divided into five zones for flocculation analysis. The increased cylinder height facilitated the flocculation of particles in the micro flocculation zone and the settling of particles in the settlement zone. The chemicals used are polyaluminum chloride (PACl), Fe₃O₄ and polyacrylamide (PAM), corresponding to doses of 60 mg/L, 40 mg/L and 6 mg/L, respectively. Insufficient insertion depth of the cone-plate will cause the small flocs that have not been fully flocculated to enter the exit pipe zone directly through the cone-plate, while too much insertion depth will cause the large floc in the settlement zone to re-enter the exit pipe zone. The flocculation effect of small flocs increased as the cone-plate spacing decreased, which is consistent with the shallow pool theory. When the cone plate spacing was too narrow, the amount of fluid was reduced and the increase in fluid velocity reduced the flocculation effect. Curve fitting was conducted for Suspended solids(SS) and turbidity removal efficiency under each structural parameter to derive the variation of SS and turbidity removal efficiency under different structural parameters. The regression models of SS and turbidity removal efficiency on the cylinder height, cone-plate insertion depth and cone-plate spacing were established based on the curve fitting results, and the regression models were verified to be well fitted based on the comparison of experimental results. Finally, the optimal values of SS and turbidity removal efficiency were found based on the regression model. The flow rate of the cone-plate clarifier is 0.6 m³/h. The SS removal efficiency reached 96.82% when the cylinder height was 708 mm, the cone-plate insertion depth was 367 mm and the cone-plate spacing was 26 mm. The turbidity removal efficiency reached 86.75% when the cylinder height was 709 mm, the cone-plate insertion depth was 369 mm and the cone-plate spacing was 26 mm. Full article

(This article belongs to the Special Issue Research on Separation Performance of Separator)

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