Mechanism of Particle Separation in Small Hydrocyclone

Hwang, Kuo‐Jen; Hsueh, Wei-Sheng; Nagase, Yoichi

doi:10.1080/07373930802175135

Cited by 23 publications

(18 citation statements)

References 14 publications

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“…The continuous classification of particles above the size of 1 lm [8][9][10][11] and the batchwise classification of small amounts of nanoparticles with microchannel technologies [12][13][14][15][16] are well developed, but for bulk products there is no apparatus available to classify nanoparticles. The required separating forces for the classification of fine particles and nanoparticles could be achieved in high-speed centrifuges.…”

Section: Introductionmentioning

confidence: 99%

Classification of Fine Particles in High‐Speed Centrifuges

Spelter

Nirschl

2010

Chem Eng & Technol

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The classification of dispersed particles below 1 lm is a difficult task due to the high surface area-to-volume ratio. Tubular-bowl centrifuges offer high centrifugal numbers, which enable the separation and classification of fine particles, biological cells and cell debris. This work presents the classification of two fine products with a mean particle size below 1 lm. Polydisperse silica and polystyrene were split successfully into a fine and a coarse fraction by a semi-continuous tubularbowl centrifuge. The fine fractions exhibited narrow particle size distributions. An optimization of the process could be achieved by a comprehensive understanding of the flow patterns, which are accessible with computational fluid dynamics. The axial and tangential velocity profiles were calculated for rotational speeds up to 40 000 rpm and throughputs ranging from 0.1 to 2 L/min. IntroductionVarious nanoparticles enhance the durability, processability and convenience of everyday products such as invisible sunscreens, coatings for displays, grinding materials, and additives for products in the chemical and construction industry [1,2]. New fields of applications have been developed due to new particle properties, e.g. superparamagnetic composites for drug delivery in cancer treatment and the recovery of valuable proteins in fermentation processes in the field of biotechnology [3]. Most of the effects originate only from the size of the particles. Coarse particles could impair the properties of the final product, e.g. rough surfaces of coatings or occlusion of the vasculature in the human body.It is possible to control the particle size during production at laboratory scale, but it is difficult to avoid reasonable amounts of particles with an undesired size in bulk products. Among the most important manufacturing processes are spray pyrolysis and grinding in stirred-media ball mills [4][5][6][7].The continuous classification of particles above the size of 1 lm [8][9][10][11] and the batchwise classification of small amounts of nanoparticles with microchannel technologies [12][13][14][15][16] are well developed, but for bulk products there is no apparatus available to classify nanoparticles. The required separating forces for the classification of fine particles and nanoparticles could be achieved in high-speed centrifuges. Tubular-bowl centrifuges offer high centrifugal numbers at throughputs of up to 10 L/min and capacities of up to 10 L. This type of centrifuge has already been used for the separation of fine particles [17,18], bacteria and viruses [19,20].The aim of this work is the determination of the classification efficiency for submicron particles and the evaluation of the flow patterns at different process parameters by computational fluid dynamics (CFD). The classification efficiency is investigated by mixing different size fractions of a polystyrene and subsequent centrifugation. The separation efficiency of the centrifuge allows splitting of the mixture into the initial fractions. Furthermore, the screening process...

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Section: Introductionmentioning

confidence: 99%

Classification of Fine Particles in High‐Speed Centrifuges

Spelter

Nirschl

2010

Chem Eng & Technol

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“…This is attributed to the underflow and particle diffusion effects (Hwang et al, 2008). Since both centrifugal and underflow effects increase their impacts by increasing the pressure drop, the entire partial separation efficiency will be improved.…”

Section: Resultsmentioning

confidence: 99%

“…The particle velocity in such a centrifugal field, u c , can be estimated using the following equation (Hwang et al, 2008): where r p is the particle density, r is the radial distance from the axial center of the hydrocyclone to the particle location, v is the angular velocity, and C D is the drag coefficient. Since the drag coefficient can be empirically correlated to the particle Reynolds number, the particle velocity can then be calculated using an iteration process (Hwang et al, 2008). Combining with the mean particle residence time in the hydrocyclone, t r , the Stokes number, Stk, can be defined as…”

Section: Resultsmentioning

confidence: 99%

“…This concept has been employed increasingly in new cyclone designs. Different kinds of hydrocyclones with diameters as small as 10-mm have been used to separate or classify fine particles in recent years (Cilliers et al, 2004;Hwang et al, 2008;Pasquier and Cilliers, 2000). However, the fish-hook phenomenon occurring on the partition curve decreases the separation sharpness for superfine particles (Cilliers et al, 2004;Hwang et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

“…Based on another viewpoint, Majumder et al (2003Majumder et al ( , 2007 claimed that the fish-hook phenomenon was due to a sudden drop in particle settling velocity based on the Reynolds number restriction. Recently, Hwang et al (2008) proposed a separation mechanism for explaining fish-hook-shape partition curves. The separation efficiency of coarse particles was determined mainly by the ''centrifugal effect'', while that of fine particles was significantly affected by the ''underflow'' and ''diffusion effects''.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Particle separation efficiency in two 10-mm hydrocyclones in series

Hwang

Lyu

Nagase

2009

Journal of the Taiwan Institute of Chemical Engineers

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Miniaturization of Hydrocyclones by High‐Resolution 3D Printing for Rapid Microparticle Separation

Han

Krasniqi

Kim

et al. 2020

Adv Materials Technologies

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principles of operation. [10][11][12] However, the effective separation of micron-scale components from biological matrices using these conventional techniques is often constrained by low throughput, biofouling, and incompatibility with the need for continuous and automated processing. [3,6,7,9] In addition, biological particles such as cells are often susceptible to damage or degradation due to the application of high forces during centrifugal or membrane based separations, presenting a further obstacle to achieving time-and cost-effective isolation of biological targets. [3,[13][14][15][16][17][18] Microfluidic-based separations based on both active and passive techniques have been investigated as promising approaches to continuous-flow isolation of micron-scale particles from fluid suspensions. Active separation methods utilize external forces including electric, [19] magnetic, [20] and acoustic forces, [21] whereas passive separation methods utilize hydrodynamic forces induced by microstructure-fluid interactions and fluid dynamic phenomena. [22][23][24] Passive separations are particularly attractive as they do not require external actuation beyond the application of bulk fluid flow through the system, thereby minimizing instrumentation requirements and system complexity. Microfluidic filtration is a straightforward strategy for particle separation utilizing sizebased retention, with an integrated membrane, micropillar array, or other porous structure able to selectively pass particles smaller than the pore size while retaining other larger particles. [25][26][27] However, as with its macroscale counterpart, filtration presents inherent challenges when handling large sample volumes, including membrane biofouling, limited throughput, high pressure requirements, and limited scaling. [26,[28][29][30] While passive hydrodynamic separation techniques such as inertial focusing, [24,31] deterministic lateral displacement, [32,33] pinched flow fractionation, [34] and Dean flow focusing [22,35,36] can overcome these constraints and are well suited to continuous flow operation, throughput remains fundamentally limited since relatively low Reynolds number flows must be employed in these systems to maintain force balance during microfluidic separations. [23,30,37] At the macroscale, hydrocyclone technology has evolved as a powerful and simple solid-liquid separation technology traditionally used in large-volume industrial processes including mineral dewatering [38,39] and desliming, [40] heavy metal recovery, [41,42] and water treatment. [43][44][45] Hydrocyclones enable Hydrocyclones are a simple and powerful particle separation technology, widely used in macroscale industrial processes, with enormous potential for miniaturization. Although recent efforts to shrink hydrocyclones to the centimeter scale have shown great promise for passive and high-throughput microparticle separations, further miniaturization is constrained by limited understanding of the impact of device size scale and design on separation performance,...

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Mechanism of Particle Separation in Small Hydrocyclone

Cited by 23 publications

References 14 publications

Classification of Fine Particles in High‐Speed Centrifuges

Classification of Fine Particles in High‐Speed Centrifuges

Particle separation efficiency in two 10-mm hydrocyclones in series

Miniaturization of Hydrocyclones by High‐Resolution 3D Printing for Rapid Microparticle Separation

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