Cylindrical Hydrocyclone Research Articles

Hydrodynamics of nonlinear viscoplastic fluid in cylindrical hydrocyclone

A flow of non-linear viscoplastic fluid film in a cylindrical hydrocyclone was simulated. The distribution of the velocity component and also a dependence of a fluid film thickness on an axial coordinate were determined by numerical solution of a set of rheodynamic model equations for various rheological properties of the liquid and dimensionless quantities. An influence of plastic properties of the liquid on damping of the circumferential component of the velocity was examined. The results were physically substantiated.

An Evaluation Index of a Hydrocyclone for Softwood Pulp Fiber Fractionation

Fractionation of softwood BCTMP pulp fiber was carried out with a cylindrical hydrocyclone. Pulp fiber length characterization in different streams have been examined using FQA. The fiber length fraction density function f is calculated and the separation index H(L) is used to evaluate fiber fractionation performance for different streams, and its specific expression was formed, so the new index may be widely used in the study of the evaluation of the separation performance of the hydrocyclone.

A Research on Separation Mechanism of Cylindrical Hydrocyclone

Using the Fiber Quantity Analyzer (FQA) for analysis of the paper pulp fiber moving in the Cylindrical Hydrocyclone, making use of the way of Limited Element Analysis and Calculation Fluid Dynamic for the numerical simulation of the velocity distribution of moving process. Based on the mathematic model of it, point out the idea of design on the geometric parameters of the cylindrical hydrocyclone. The result show, the suit length of pole is benefit to improve the machine handle ability and separation efficiency.

A Research on Separation Mechanism of Cylindrical Hydrocyclone

A Research on Separation Mechanism of Cylindrical Hydrocyclone

Numerical study on oil and water two-phase flow in a cylindrical cyclone

Although traditional hydrocyclones are widely used in industries, there are few studies on cylindrical hydrocyclone. In this work, Euler-Euler multiphase approach and the Reynolds stress turbulence model (RSM) are applied to simulate the flow field characteristic of cylindrical cyclone. The result shows that a low pressure zone is formed in the inner part of cyclone and causes an upward flow. Velocity components distribution, tangential velocity, axial velocity and radial velocity have been calculated to study the effect of oil-water separation efficiency of cylindrical cyclone under the conditions of different flow split-ratio and non-dimensional separation acceleration. These results are helpful to design a separator system in the oil production.

Development of a simple experimental method for the determination of the liquid field velocity in conical and cylindrical hydrocyclones

The objective of this work was to propose a new and simple method to understand the hydrodynamic phenomena that occur within two types of hydrocyclones, cylindrical and conical. Using a PCO 1200 hs digital high-speed camera, this method involved the following of a little red oil droplet that had been injected by a small syringe into the hydrocyclone at different zones. The trajectory line of the injected droplets and velocity of the water were investigated, in terms of the tangential and axial velocities of the water and the average velocity gradient in the hydrocyclone. In both hydrocyclones, if the oil droplets were injected at the center of the hydrocyclone, they went down to the bottom part of the hydrocyclone. In contrast, if the droplets were injected close to the wall of the hydrocyclone, they rose rapidly to the upper part of the hydrocyclone. Moreover, the tangential velocity of water in both hydrocyclones presented average velocity gradient of the water at the center of the hydrocyclone which was significantly lower than the average velocity gradient of the water close to the wall of hydrocyclone. Therefore, it could be concluded that the external vortex close to the wall of the hydrocyclone was stronger than the internal vortex at the center of the hydrocyclone. These obtained results are in agreement with those observations in the literatures. In conclusion, we propose this simple experimental method as an effective means of understanding the hydrodynamic phenomena that occurs within hydrocyclones and so improving the hydrocyclone design for further applications.

Analysis of influence exerted by structural and regime parameters of cylindrical hydrocyclones on degassing efficiency of non-Newtonian media on the basis of regression model

A procedure is developed for calculation of separation indicators for the degassing of liquids possessing non-Newtonian properties in a cylindrical hydrocyclone using a regression model. The effect of determining similitude numbers characterizing the degassing of non-Newtonian liquids in a cylindrical hydrocyclone and the rheologic properties of the liquid on the distribution of the extent to which gas bubbles are extracted over the height of the effective space of the hydrocyclone is analyzed. The procedure proposed for calculation of separation indicators will permit well-founded selection of structural parameters and operating regimes in the design stage of a hydrocyclone employed for the degassing of non-Newtonian liquids.

Simulation of suspension separation by two-stage pressure-head flotation in a cylindrical direct-flow hydrocyclone

A mathematical model of separation of suspensions with a non-Newtonian dispersion medium by two-stage pressure-head flotation in a cylindrical direct-flow hydrocyclone was developed. A system of differential equations describing convective diffusion and motion of a particle-bubble complex was solved numerically. The concentration field was modeled and integral separation parameters were determined.

Selection of structural parameters for a cylindrical hydrocyclone for degassing of heterogenous liquid media based on results of numerical modeling

Recommendations for optimization of structural parameters of a cylindrical hydrocyclone used to degas heterogeneous liquid media possessing non-Newtonian properties are set forth on the basis of results of numerical modeling. The mathematical degassing model takes into account the effect of inertial and Coriolis forces, and the associated liquid mass during the movement of a gas bubble. A system of differential equations in partial derivatives, which describes the degassing of heterogeneous media in a hydrocyclone, is reduced to ordinary differential equations, and is solved by the numerical method. The influence exerted on the degassing process by structural parameters of a cylindrical hydrocyclone and rheologic properties of the liquid is analyzed.

1655 円筒型液体サイクロンの流動・分離性能(G05-9 流体機械(2),G05 流体工学)

1655 円筒型液体サイクロンの流動・分離性能(G05-9 流体機械(2),G05 流体工学)

Numerical modeling of highly swirling flows in a through‐flow cylindrical hydrocyclone

AbstractThis article aims to identify the most appropriate numerical methodology for simulating hydrocyclone flows with high swirl numbers. The numerical results are validated against the tangential velocity measurements from a cylindrical hydrocyclone with a swirl number of 8.1, which is twice the typical swirl magnitude of industrial hydrocyclones. The linear and quadratic formulations of the Reynolds stress transport (RST) model are used to simulate the anisotropic swirling turbulent flow three‐dimensionally in the commercial software package Fluent™. The tangential velocity profiles predicted by the quadratic RST model are in good agreement with experimental data. They also show Rankine vortex patterns over the entire flow domain. In contrast, the linear RST model fails to predict this important swirl flow feature. In addition, both models predicted a complex axial flow reversal pattern not previously reported in hydrocyclones. This study clearly shows that the quadratic RST model is preferable for future hydrocyclone simulations, especially when the swirl number is large. All necessary physical and numerical parameters used to obtain converged results are given in this article. © American Institute of Chemical Engineers AIChE J, 2006

Evaluation of Fractionation of Softwood Pulp in a Cylindrical Hydrocyclone

Pulp fiber length characterization is addressed in this article. It is suggested that the proposed separation index H(L) is a viable index to the fiber fractionation performance for evaluating hydrocyclones. Fractionation of softwood (coniferous wood) bleached chemithermomechanical pulp (BCTMP) fiber was carried out with a cylindrical hydrocyclone. Pulp fiber length characteristics in different streams were examined using the fiber quality analyzer (FQA), and the cumulative fiber length fraction, the fiber length fraction density function and the separation index H(L) for different streams were obtained. It is found that H(L) is very useful for characterizing the fiber fractionation performance by indicating the separation capacity of hydrocyclone for individual subgroup of fibers in different streams under different operation conditions. Results of H(L) show that there exists a critical fiber length. A higher proportion of fibers longer than the critical fiber length is in the overflow stream, and a higher proportion of fibers shorter than the critical fiber length in the underflow stream. The data obtained from FQA suggest that the split ratio is the most significant parameter for fiber fractionation performance, which is the best when the split ratio is in the range between 0.14 and 0.2. The effect of feed rate on fiber fractionation performance is weak.

Velocity measurements in a cylindrical hydrocyclone operated with an opaque fiber suspension

Two novel techniques to measure velocity in opaque pulp fiber suspensions have been evaluated in a hydrocyclone. A pitometer equipped with a medical micropressure transducer was used to record the tangential velocity. The pressure opening of the pitometer was kept clean with a small purge flow. The small size of the probe minimized its influence on the flow field. The pitometer was able to measure the tangential velocity in the fiber suspension at different levels in the hydrocyclone. Additionally, a non-intrusive ultrasonic velocity profiler (UVP) was used to measure the radial particle velocity. The UVP proved to be capable of measuring radial particle velocity profiles.

Velocity measurements in a cylindrical hydrocyclone operated with an opaque fiber suspension

Two novel techniques to measure velocity in opaque pulp fiber suspensions have been evaluated in a hydrocyclone. A pitometer equipped with a medical micropressure transducer was used to record the tangential velocity. The pressure opening of the pitometer was kept clean with a small purge flow. The small size of the probe minimized its influence on the flow field. The pitometer was able to measure the tangential velocity in the fiber suspension at different levels in the hydrocyclone. Additionally, a non-intrusive ultrasonic velocity profiler (UVP) was used to measure the radial particle velocity. The UVP proved to be capable of measuring radial particle velocity profiles.

Analysis of Degree of Extraction of Solid-Phase Particles during Separation of Non-Newtonian Suspensions in a Cylindrical Direct-Flow Hydrocyclone with Forced Flotation

Analysis of Degree of Extraction of Solid-Phase Particles during Separation of Non-Newtonian Suspensions in a Cylindrical Direct-Flow Hydrocyclone with Forced Flotation

Modeling of Separation in a Cocurrent Cylindrical Hydrocyclone

The radial motion of the dispersed phase in a cocurrent cylindrical hydrocyclone under the action of deterministic forces, including the inertial force, is considered. It is shown that the acceleration of particles in the direction away from the apparatus axis toward the apparatus wall can be neglected. Under this assumption, a method is proposed to calculate the characteristics of separation of the solid–liquid and solid–liquid–gas systems.

Flow patterns in conical and cylindrical hydrocyclones

Using a two beam, 300 mW laser Doppler velocimeter, the tangential and axial velocity fields were determined for the water flow in a 102-mm modular hydrocyclone. The body of the equipment could be changed to transform it into a conical or a flat bottom hydrocyclone. During the tests the pressure drop and the diameter of apex and vortex were varied and the axial and the tangential velocities and their turbulence intensity were measured. The results shows that the inlet pressure affects only the magnitude of the velocities, but does not change the flow pattern. The tangential velocity is similar in both types of hydrocylones while the axial velocity is different. In both hydrocyclones the axial velocity is a function of the radial position but, while it is a linear function of the vertical coordinate in the cylindrical hydrocyclone, this is not the case for the conical vessel.

Comparison between Flow Velocity Profiles in Conical and Cylindrical Hydrocyclones

Comparison between Flow Velocity Profiles in Conical and Cylindrical Hydrocyclones

Drop size measurement in a two-phase swirling flow using image processing techniques

An experimental study of two-liquid swirling flows in a cylindrical hydrocyclone was conducted using flow visualization and digital image processing. The flow pattern was recorded using a video camera and the resulting flow images at cross-sectional planes were digitized in a personal computer. A technique was developed to measure drop sizes and areas using image enhancement and segmentation techniques. The image was cleaned of noise using a set of image processing algorithms. These algorithms included background noise subtraction, contrast enhancement, median and smoothing filters and gray level thresholding, and had to be applied in that order for accurate drop size measurement. The errors and the uncertainties associated with the technique have been addressed. For the range of oil and water flow rates studied, it was seen that the concentration of oil in any plane of cross section of the cyclone reaches a constant value. For the low flow rates studied, the cyclone behaved more as a mixer than a separator due to a weaker radial pressure gradient. Hence, a simple first order model was used to predict time constants for the two water flow rates used. The possibility of introducing this time constant as a suitable time scale was investigated. An attempt was also made to normalize the data using oil-water flow rate as a parameter. There was not sufficient evidence to show that such a ratio could be a flow parameter in this problem.

Method for calculation of separation indexes of suspensions in a cylindrical cocurrent hydrocyclone

Method for calculation of separation indexes of suspensions in a cylindrical cocurrent hydrocyclone