The following performance between particle and fluid medium inside hydrocyclone with double vortex finders

In this paper, we used numerical simulations to study the effect of size, density and concentration of particles on the relative motion between two phases in a cyclone separator with double vortex finders, which is different than a traditional separator that has only one overflow pipe

Study on effect of the inner vortex finder length on the flow properties of the hydrocyclone with double vortex finders

The traditional hydrocyclone can only obtain two products: overflow and underflow. In the paper, we propose three-products hydrocyclone with double vortex finders. The hydrocyclone is designed with two coaxial overflow tubes with different diameters. During overflow, light and fine particles exit from the inner overflow tube. The mid-size particles overflow from the outer overflow tube, and the coarse particles through the underflow pipe. Therefore, one classification can obtain three different narrow-grade-classification products. The inner vortex finder length is the important influent factor on the flow performance of the hydrocyclone. This paper is mainly focused on the study of the flow field of both the air and the liquid phase, and of the effects of the inner vortex finder length on the velocity field, pressure field and the air column of the hydrocyclone with double vortex finders

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

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

Sediment-Containing Sewage Separation Using Intermittent-Discharge Columnar Hydrocyclones

Traditional hydrocyclones can be used for the concentration of sewage-containing sediments, but the low underflow concentration and the high content of fine particles result in a large subsequent dehydration workload. This study aimed to investigate the effect of columnar hydrocyclone column height on separation performance and the change in the internal flow field after the underflow orifice of the hydrocyclone was closed, so as to provide a theoretical basis for improving the ability to treat the sewage of the hydrocyclone. Numerical simulation was used to examine the change in the separation performance of the hydrocyclone and the effect of column height on the separation performance of the hydrocyclone in the case of the closed underflow orifice during intermittent discharging. The results indicate that a proper increase in column height was beneficial to improve the separation performance of the hydrocyclone. With the increase in the closing time of the underflow orifice, the particle content at the bottom of the hydrocyclone increased significantly. The experiment proves the feasibility of the intermittent discharge method in practice, and this working method can effectively increase the underflow concentration

Numerical simulation of multiphase flow inside hydrocyclone based on CFD

Abstract This paper applied computational fluid dynamics (CFD) method to investigate the internal multiphase flow filed in a 75 mm hydrocyclone. The Reynolds stress model (RSM) and VOF model were employed in the numerical simulation. This study discussed the velocity and pressure distribution in the hydrocyclone, and analysed the formation and development mechanism of air core. The numerical simulation results showed that the flow field was very unstable in the region of the air core. The axial velocity gradient reached its maxima, and the turbulent fluctuation was strongest in the simulation region. This study provided theoretical basis on further research of the air core effect on separation efficiency and pressure drop

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

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

The Study on Numerical Simulation and Experiments of Four Product Hydrocyclone with Double Vortex Finders

A hydrocyclone is an instrument that can effectively separate multi-phase mixtures of particles with different densities or sizes based on centrifugal sedimentation principles. However, conventional hydrocyclones lead to two products only, resulting in an over-wide particle size range that does not meet the requirements of subsequent operations. In this article, a two-stage series, a four product hydrocyclone is proposed. The first stage hydrocyclone is designed to be a coaxial double overflow pipe: under the effect of separation, fine particles are discharged from the internal overflow pipe, while medium-size particles are discharged from external overflow pipe before entering the second stage hydrocyclone for fine sedimentation. In other words, one-stage grading leads to four products, including the first stage underflow, the first stage overflow, the second stage underflow, and the second stage overflow. The effects of structural parameters and operational parameters on flow field distribution in hydrocyclone were investigated via a study of flow field distribution in multi-product hydrocyclones using numerical simulations. The application of four product hydrocyclone in iron recovery shows that the grade and recovery of iron concentrate exceed 65.08% and 86.14%, respectively. This study provides references for understanding the flow field distribution in hydrocyclones and development of multi-product grading instrument in terms of both theory and industrial applications

Interface Bonding Properties of CrAlSiN-Coated Cemented Carbides Doped with CeO₂ and Y₂O₃ Rare Earth Oxides

This study performed first-principle-based calculations of the interface adhesion work in interface models of three terminal systems: CrAlSiNSi/WC-Co, CrAlSiNN/WC-Co, and CrAlSiNAl/WC-Co. The results proved that the CrAlSiNSi/WC-Co and CrAlSiNAl/WC-Co interface models had the highest and lowest interface adhesion work values (4.312 and 2.536 J·m−2), respectively. Thus, the latter model had the weakest interface bonding property. On this basis, rare earth oxides CeO2 and Y2O3 were doped into the Al terminal model (CrAlSiNAl/WC-Co). Then, doping models of CeO2 and Y2O3 doped on the WC/WC, WC/Co, and CrAlSiNAl/WC-Co interfaces were established. The adhesion work value was calculated for the interfaces in each doping model. When CeO2 and Y2O3 were doped in the WC/WC and CrAlSiNAl/WC-Co interfaces, four doping models were constructed, each model contains interfaces withreduced adhesion work values, indicating deteriorated interface bonding properties. When the WC/Co interface was doped with CeO2 and Y2O3, the interface adhesion work values of the two doping models are both increased, and Y2O3 doping improved the bonding properties of the Al terminal model (CrAlSiNAl/WC-Co) more significantly than CeO2 doping. Next, the charge density difference and the average Mulliken bond population were estimated. The WC/WC and CrAlSiNAl/WC-Co interfaces doped with CeO2 or Y2O3, with decreased adhesion work, exhibited low electron cloud superposition and reduced values of charge transfer, average bond population, and interatomic interaction. When the WC/Co interface was doped with CeO2 or Y2O3, superposition of the atomic charge densities of electron clouds was consistently observed at the CrAlSiNAl/WC-Co interface in the CrAlSiNAl/WC/CeO2/Co and CrAlSiNAl/WC/Y2O3/Co models; the atomic interactions were strong, and the interface bonding strength increased. When the WC/Co interface was doped with Y2O3, the superposition of atomic charge densities and the atomic interactions were stronger than for CeO2 doping. In addition, the average Mulliken bond population and the atomic stability were also higher, and the doping effect was better