Fish hook effect in centrifugal classifiers – a further analysis

Nageswararao, K.; Medronho, Ricardo de Andrade

doi:10.1016/j.minpro.2014.09.002

Cited by 20 publications

(5 citation statements)

References 70 publications

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“…It is worth noting that the fish-hook phenomenon appears at different locations for the two kinds of dust, which may be related to the different agglomeration abilities of the two dust. 52,55,56 The average particle size of the molecular sieve particles is smaller than that of the white carbon black ones. As such, the "fish-hook" for the molecular sieve appears at about 1.75 μm, while that for the white carbon black appears later at 2.30 μm.…”

Section: Resultsmentioning

confidence: 99%

A New Fine Particle Removal Technology: Cloud-Air-Purifying

Wang

Dong

et al. 2018

Ind. Eng. Chem. Res.

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This paper presents an innovative dust removal technology, Cloud-Air-Purifying (CAP), which combines electro-acoustic ultrasonic nebulization with a cyclone dust collector. A humid environment is produced in the cyclone to imitate natural clouds in which the rain drops are formed. This facilitates the ultrafine particles in the environment to absorb moisture and agglomerate. Consequently, the ultrafine particles will significantly increase in size and thus be much more efficiently collected by the cyclone. Experimental results of the collection of two kinds of particles show that CAP significantly improves the collection efficiency of PM2.5 particles compared to traditional gas cyclones. Furthermore, numerical simulation is used to study the dynamics of the fine particles in CAP environment, which verifies the positive effect of particle growth on the collection efficiency. Finally, the successful industrial applications of CAP technology are demonstrated. This paper confirms CAP as a novel and effective method for controlling air pollution.

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Section: Resultsmentioning

confidence: 99%

A New Fine Particle Removal Technology: Cloud-Air-Purifying

Wang

Dong

et al. 2018

Ind. Eng. Chem. Res.

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“…Using the Discrete Phase Model (DPM) particle trajectories of particles of different sizes were then determined and conclusions were drawn about Various researchers have attempted this so far, not only for centrifugal classifier but also for similar apparatus like cyclones. Nagaswararao et al [15] summarize previous studies and draw the following conclusion. There is no uniform consensus in literature for the occurrence of the fish-hooks effect.…”

Section: Introductionmentioning

confidence: 81%

“…In the second theory it is assumed that fine particles acquire velocities larger than the Stokes velocity when entrained by coarse particles [16]. In addition, the fish-hook effect occurs more frequently in measurements when the sizing analyses are carried out by Laser diffractometry using his optical mode [15].…”

Section: Introductionmentioning

confidence: 99%

Development of a New Solver to Model the Fish-Hook Effect in a Centrifugal Classifier

2021

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Centrifugal air classifiers are often used for classification of particle gas flows in the mineral industry and various other sectors. In this paper, a new solver based on the multiphase particle-in-cell (MP-PIC) method, which takes into account an interaction between particles, is presented. This makes it possible to investigate the flow process in the classifier in more detail, especially the influence of solid load on the flow profile and the fish-hook effect that sometimes occurs. Depending on the operating conditions, the fish-hook sometimes occurs in such apparatus and lead to a reduction in classification efficiency. Therefore, a better understanding and a representation of the fish-hook in numerical simulations is of great interest. The results of the simulation method are compared with results of previous simulation method, where particle–particle interactions are neglected. Moreover, a validation of the numerical simulations is carried out by comparing experimental data from a laboratory plant based on characteristic values such as pressure loss and classification efficiency. The comparison with experimental data shows that both methods provide similar good values for the classification efficiency d50; however, the fish-hook effect is only reproduced when particle-particle interaction is taken into account. The particle movement prove that the fish-hook effect is due to a strong concentration accumulation in the outer area of the classifier. These particle accumulations block the radial transport of fine particles into the classifier, which are then entrained by coarser particles into the coarse material.

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“…The authors reported much difficulty in achieving convergence with Reynolds stress model (RSM). Nageswararao and Medronho (2014) compiled a review of the various studies regarding fish-hook phenomenon in classifiers.…”

Section: Literature Reviewmentioning

confidence: 99%

Numerical investigations on particle separation in dynamic separators

Appadurai¹,

Raghavan

2019

HFF

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Purpose Dynamic separator is an equipment having a rotor and static vanes and is used to separate solids from gas-solids flow based on size. Particle separation in a dynamic separator happens due to complex interchanges between multiple forces exerted in the separation zone. Currently, there is only limited knowledge concerning the working principles of separation. This paper aims to systematically study a dynamic separator using numerical models to get insights into particle separation. Design/methodology/approach The Lagrangian–Eulerian formulation is used to simulate gas-solid flow. Multiple frames of reference using stage interpolation are used to account for rotation. Periodic symmetry in the equipment is exploited to create a simplified numerical model. The predictions from the numerical model are compared against available experimental data. Findings The numerical results indicate that only when particle collision is included, the separation efficiency trend from the experiment is matched by numerical predictions. Further, it is shown that at the same range of rotor speeds where numerical results predict increased separation efficiency, the solid pressure due to particle collision also reaches its maximum value. The gas flow and particle behavior in the separator are explained in detail. Originality/value The importance of particle collision in separation is interesting because traditionally, particle separation is assumed to be influenced by three forces, namely, centrifugal force, drag force and gravity. The numerical results, however, point to the contribution by particle collision, in addition to the above three forces.

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Fish hook effect in centrifugal classifiers – a further analysis

Cited by 20 publications

References 70 publications

A New Fine Particle Removal Technology: Cloud-Air-Purifying

A New Fine Particle Removal Technology: Cloud-Air-Purifying

Development of a New Solver to Model the Fish-Hook Effect in a Centrifugal Classifier

Numerical investigations on particle separation in dynamic separators

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