The segregation pattern of a binary mixture of particles is studied in a continuous fast-fluidized bed of 3.65 m height and 69 mm ID. The influence of operating variables such as gas velocity, solids feed rate and feed composition on total solids holdup and axial solids holdup is studied. Empirical correlations are proposed for the total pressure drop in the fast fluidization regime when density and/or size segregation occur. The influence of the operating variables on the axial concentration of solids in both the dense and dilute phases is analyzed. © 2010 Elsevier B.V. All rights reserved.

P Sesha Talpa Sai

Department Of Chemical Engineering

AXIAL SOLIDS HOLDUP

BINARY SOLIDS

DENSITY SEGREGATION

FAST FLUIDIZATION

SOLIDS CONCENTRATIONS

SOLIDS HOLDUPS

Binary mixtures

Concentration (process)

FLUID DYNAMICS

Fluidization

Pressure drop

Segregation (metallography)

Fluidized beds

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IIT Madras

Chemical Engineering Journal

Continuous segregation of homogeneous binary mixture of solids was experimentally investigated in a liquid fluidised bed with water as the fluidising medium. Experiments were conducted to study the influence of operating variables such as feed rate of solids, feed composition and liquid superficial velocity on pressure drop, entrainment and discharge rates of solids, and purity of top and bottom products. The fluidisation phenomenon was observed through pressure drop measurements and the liquid velocity range for the classification of solids was identified. Correlations are proposed for the entrainment rate of solids, and purity of top and bottom products. When solid particles are in a fluid-like state, there exists an equilibrium between released flotsam component and residual jetsam component at steady state. © 2019, © 2019 Indian Institute of Chemical Engineers.

Indian Chemical Engineer

Continuous segregation of homogeneous binary mixture of solids by a liquid fluidised bed classifier

Continuous segregation of binary heterogeneous solids (different density mixtures) is carried out in a gas–solid fluidized bed to study the effects of gas velocity, solids feed rate, feed composition and density difference of solids on the separation factor (recovery of flotsam at top outlet) and the quality of the product (purity of flotsam at top outlet) in a continuous fast-fluidized bed. The holdup of the bed material is obtained in each experimental run. It is observed that the separation factor decreases with increase in solids feed rate or density difference of solids, and increases with gas velocity or proportion of flotsam in the feed. The quality of the product decreases with increase in gas velocity or solids flow rate, and increases with feed composition or density difference of solids. The experimental results show that the separation factor and the quality of the product are more sensitive to gas velocity than to other operating parameters. Empirical correlations for predicting the separation factor and quality of the product are proposed based on the Richards model for individual flotsam mass fraction in the feed, and the predictions agree satisfactorily with the present experimental data. © 2017 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences

Particuology

Continuous segregation of binary heterogeneous solids in a fast-fluidized bed

Continuous segregation of a binary mixture of heterogeneous (different density) solids is carried out in a gas–solid fluidized bed. We investigate how gas velocity, solids feed rate, flotsam feed composition, bottom discharge pipe diameter, and minimum fluidization velocity ratio of the flotsam to jetsam particles influence the solids holdup, separation factor, and product quality (flotsam purity at the top outlet). The results are interpreted in terms of solids holdup information. The results indicate that the separation factor decreases when the gas velocity, bottom discharge pipe diameter, flotsam feed composition, or the minimum fluidization velocity ratio increase, while the separation factor increases as the solids feed rate increases. The product quality decreases when the gas velocity, solids feed rate, or minimum fluidization velocity ratio increase, while the product quality increases as the bottom discharge pipe diameter or flotsam feed composition increase. Correlations for predicting the separation factor and product quality are proposed using a logistic model for individual flotsam feed compositions, which satisfactorily compares with the present experimental data. © 2017 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences

Continuous segregation of binary heterogeneous solids in fluidized beds

Studies on the influence of feed entry on segregation using continuous fast fluidization is not clearly understood even though studies are available on the segregation of particles in continuous bubbling/turbulent fluidized beds. In the present study, four different feed inlet positions are selected and tested in a 69 mm ID and 3.65 m height continuous fast fluidized bed. The feed is a binary mixture of solid particles of the same size, but different density. The inimitable observations noticed at various feed locations on fluidization behavior with segregation is discussed. Change in the feed inlet height of the fluidized bed is reflected drastically on the compositions of top and bottom products. Disparate behavior of continuous fluidization is noticed at selected feed inlet positions. Operation is not stable due to either particle congestion in the feeding line or nonuniform discharge of solids from the fluidized bed when the feed inlet position is located close to distributor. Further an enhanced-feed inlet location created a particles cloud above the dense phase. Excess of feed inlet height transformed the binary mixture severance and freeboard height. The optimum operating gas velocity required for maximum separation of both species is identified at every feed entry for different feed rates. A unique feed entry location is recognized for maximum separation of both the species and minimum gas. © 2011 American Chemical Society.

Industrial and Engineering Chemistry Research

Influence of feed entry on the segregation of a binary mixture of solids in a continuous fast fluidized bed

Segregation of binary mixture of solids was experimentally investigated in a continuous fast fluidized bed of 69 mm i.d. and 3.65 m high with air as the separation medium. The feed is a binary mixture of solid particles of same size, but different density. The variables include superficial gas velocity, solids feed rate and feed composition. It was observed that, at steady state, there exists physical equilibrium between the evolved flotsam and the residual jetsam when the granular solids are in fluid-like state. The phase diagram was constructed from the experimental observations. It shows the range for segregation, behavior of the fluidized bed and the distribution of the flotsam and jetsam, which can be understood by analogy with the distillation of the binary liquid mixture. The effect of the solids feed rate and feed composition on equilibrium distribution of the flotsam and jetsam was studied. © 2007 Elsevier B.V. All rights reserved.

Studies on segregation of binary mixture of solids in a continuous fast fluidized bed. Part I. Effect of particle density

Experimental investigations on the continuous fast fluidized bed were extended for size segregation of binary mixture of solids in the column with air as the separation medium [1]. The feed is either jetsam-rich or flotsam-rich binary mixture of particles of different size, but same density. The variables tested were superficial gas velocity, solids feed rate and feed characteristics. At steady state, there exists physical equilibrium between the evolved flotsam and the residual jetsam when the granular solids are in fluid-like state as in the case of density segregation of solids [1]. Using the analogy of the binary liquid mixtures separation by distillation, the phase diagram was constructed from the experimental observations. The effect of solids feed rate, feed composition, particle size ratio and particle size on equilibrium distribution of the flotsam and jetsam were presented. © 2007 Elsevier B.V. All rights reserved.

Studies on segregation of binary mixture of solids in continuous fast fluidized bed. Part II. Effect of particle size

Segregation of particles due to difference in either size or density was studied in a continuous fast fluidized bed of 69 mm ID and 3.65 m height [1]. Binary feed mixtures of either flotsam-rich or intermediary or jetsam-rich mixtures were utilized for the study. The influence of the operating variables on the particles segregation was examined. All the considered feed mixtures, showed similar segregation effect even though the fluidization behavior of the binary mixtures differ [1,2]. Empirical correlations were suggested for the entrainment of solids and purity of the top and bottom products for all the three categories of binary feed mixtures considered. The optimum gas velocity for maximum separation of the lighter/fine and heavier/coarse particles is identified. The effect of the operating variables on the identified optimum gas velocity and optimum purity/recovery is presented. © 2008 Elsevier B.V. All rights reserved.

Studies on segregation of binary mixture of solids in continuous fast fluidized bed. Part III. Quantification of performance of the segregator

Chemical Engineering Science

Hydrodynamics of gas–solid fluidized bed of disparately sized binary particles

Axial voidage profiles and identification of flow regimes in the riser of a circulating fluidized bed

Studies on segregation of binary mixture of solids in a continuous fast-fluidized bed. Part IV. Total solids holdup, axial solids holdup and axial solids concentration

Journal	Chemical Engineering Journal
ISSN	13858947
Open Access	No