Velocity characterization of solids in binary fluidized beds

Roy, Shantanu; Pant, H.J.; Roy, Shantanu

doi:10.1016/j.ces.2021.116883

Cited by 8 publications

(9 citation statements)

References 54 publications

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“…Detailed methodology for the calculation of RPT quantities can be found elsewhere. [40][41][42] 3 | CFD MODELLING…”

Section: Radioactive Particle Tracking (Rpt)mentioning

confidence: 99%

Modelling of binary fluidization of coal and ash and validation using radioactive particle tracking and densitometry

Roy

2022

Can J Chem Eng

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Binary fluidization finds wide application in a variety of gas–solid catalytic and non‐catalytic industrial fluidization systems. In the present study, a three‐dimensional transient computational fluid dynamics (CFD) model was used to model the binary fluidization of coal and ash in a laboratory‐scale cold flow fluidized bed. In parallel, phase velocity measurements using radioactive particle tracking (RPT) and gamma‐ray densitometry were performed, which provided a rich database for validation of the CFD model. RPT being a time‐resolved Lagrangian technique, it was possible to extract velocity fluctuations and their correlations in addition to the mean velocity profiles. The latter provided additional validation for the CFD model, in addition to the typical validation that is done with time‐averaged profiles of phase velocity and volume fraction. The robust validation procedure opens up the possibility of expanding this model to a pilot plant‐scale fluidized bed.

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“…Detailed methodology for the calculation of RPT quantities can be found elsewhere. [40][41][42] 3 | CFD MODELLING…”

Section: Radioactive Particle Tracking (Rpt)mentioning

confidence: 99%

Modelling of binary fluidization of coal and ash and validation using radioactive particle tracking and densitometry

Roy

2022

Can J Chem Eng

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“…Gas-solid (GS) fluidized beds have been important in various applications, such as drying (Yohana et al, 2020), granulation (Behzadi et al, 2009), blending, combustion, gasification (Roy et al, 2021), and conversion of methanol to olefins (Chang et al, 2019), for more than seven decades. One of the several advantages of fluidized beds over fixed beds is their ability to be operated isothermally, with minimal axial temperature gradients (Menéndez et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

“…A major challenge in binary systems is that the beds reach equilibrium with either mixing or segregation of particles as two extremes. These dynamics are studied using advanced experimental techniques that include non-intrusive methods like tomography, radioactive particle tracking (RPT) (Roy et al, 2021), and intrusive techniques that include pressure probes for measuring pressure drops and quality of fluidization, and optical probes for measuring particle diameter, particle velocity, etc. Dynamics and transport phenomena in fluidized beds have also been studied both qualitatively and quantitatively using computational fluid dynamics (CFD) (mostly Eulerian-Eulerian approaches)/mathematical modeling (Cooper and Coronella, 2005;Du et al, 2006;Gao et al, 2009;Pei et al, 2010;Zaabout et al, 2010;Chang et al, 2012;Mostafazadeh et al, 2013;Benzarti et al, 2014;Sahoo and Sahoo, 2016;Bakshi et al, 2017;Agrawal et al, 2018;Chang et al, 2019;Daryus et al, 2019;Khezri et al, 2019;Shrestha et al, 2019;Kotoky et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

CFD simulations to study bed characteristics in gas–Solid fluidized beds with binary mixtures of Geldart-B particles: A qualitative analysis

Ganguli

Bhatt²

2023

Front. Energy Res.

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The bed dynamics of unary and binary fluidized beds play a key role in understanding the pressure drop and hence provides an opportunity for performance improvement of the beds. In the present work, characteristics of fluidized beds with binary mixtures of Geldart-B particles were investigated using CFD simulations. The phenomena of segregation and mixing using simulations were studied, both qualitatively and quantitatively, at a range of superficial gas velocities (0.3–0.6 m/s) and two different bed heights. The study was divided into two parts. In Part I, the current study, a qualitative analysis of flow patterns for seven different binary mixtures, is presented. The quantitative analysis, including particle and gas velocity profiles, particle volume fraction profiles, and correlations for minimum fluidization velocity and pressure drop, will be presented in Part II of this work. A mathematical model consisting of an Eulerian-Eulerian model with RNG k-ε model and KTGF model to capture the bubble dynamics was used. The standardized values of coefficients and plastic stresses have been used for all simulations. The CFD model was validated using experimental data from the literature. Qualitative predictions of volume fraction profiles of small-sized particles showed that, for mixtures within a range of 40%–60% Geldart-B type large particles, the bubble and solid particle dynamics were different from those of single particles of the superficial gas velocities considered. In contrast to the single particles in the given superficial gas velocity range that were in bubbling regime, the binary particles showed a transition from bubbling to slugging to turbulent regime, as demonstrated by qualitative analysis. A homogeneous regime was observed for lower superficial gas velocities for mixtures consisting of 0%–20% large particles.

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“…A major challenge in binary systems is that the beds reach equilibrium with either mixing or segregation of particles as two extremes. In applications like coal gasification, where synthetic gas (syngas) is the desired output, the segregation of particles may lead to the coal particles remaining unreacted, reducing the syngas yield (Roy et al, 2021). Furthermore, segregation is observed when binary mixtures of particles with varying densities are present in the bed, whereas mixing is observed when mixtures of varying sizes are present.…”

Section: Introductionmentioning

confidence: 99%

“…In such beds, the bubbles rise through the center of the bed, and the rise velocity of the bubbles increases with the superficial velocity of the gas. Recently, interesting and significant progress in studies on bed dynamics of binary fluidized beds using experimental techniques for bubbling fluidized beds related to velocity distribution of bubble and solid particles (both flotsam and jetsam) have been carried out (Zhang et al, 2017;Kalo et al, 2019;Singh et al, 2019;Roy et al, 2021). The bed dynamics of fluidized beds with binary mixtures have been studied by advanced experimental techniques that include non-intrusive techniques like 1. electrical capacitance tomography (ECT) (Singh et al, 2019), 2. radioactive particle tracking (RPT) (Roy et al, 2021), 3. digital image analysis, 4. magnetic resonance imaging (MRI), and 5. positron emission particle tracking and intrusive techniques like 1. pressure probes for measuring pressure drops and quality of fluidization and 2. optical probes for measuring particle diameter, particle velocity, etc.…”

Section: Introductionmentioning

confidence: 99%

CFD simulations to study bed characteristics in gas–solid fluidized beds with binary mixtures of Geldart B particles: II quantitative analysis

Ganguli

Bhatt

2023

Front. Energy Res.

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Hydrodynamics of fluidized beds with binary mixtures of particles is important in many industrial applications. The binary particles are generally in the Geldart particle range. In our earlier work, (Part I) of this work simulations were carried out and qualitative analysis was presented. Quantitative predictions of gas velocity and particle velocity profiles have been presented in the present work, which is Part II of the two-part work on computational fluid dynamics (CFD) simulations of binary fluidized beds. It was observed that the dynamics of the bed vary for different binary mixtures and are a strong function of superficial velocity and bed height. Mixing and segregation in beds for two different initial bed heights and six different binary mixtures and superficial velocities have been identified. Segregation is prominent for binary mixtures with 20 wt.% and 80 wt.% of large particles, whereas mixing is observed in 40 wt.% and 60 wt.% large particle mixtures. Bypassing of gas near the walls is prominently seen for 60 wt.% large particles with gas velocities as high as 5 m/s. Time-averaged axial particle volume fractions have been observed to be lower in the dilute phase with large undulations in the middle whenever the bed is well mixed for central axial profiles. The axial volume fraction profiles also confirm the mixing and segregation for the 40 wt.% and 20 wt.% composition of large particles for the operating conditions considered for the study. Bed height expansion is linear until a certain superficial velocity with the increase or decrease depending on the superficial velocity or bed height of operation. Furthermore, correlations for minimum fluidization velocity and pressure drops from the literature have been compared with experimental results. The simulated data have been considered for the development of a correlation for minimum fluidization velocity. The predicted results match experimental data with a 10%–15% deviation.

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Velocity characterization of solids in binary fluidized beds

Cited by 8 publications

References 54 publications

Modelling of binary fluidization of coal and ash and validation using radioactive particle tracking and densitometry

Modelling of binary fluidization of coal and ash and validation using radioactive particle tracking and densitometry

CFD simulations to study bed characteristics in gas–Solid fluidized beds with binary mixtures of Geldart-B particles: A qualitative analysis

CFD simulations to study bed characteristics in gas–solid fluidized beds with binary mixtures of Geldart B particles: II quantitative analysis

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