Numerical investigation on the hydrodynamics of an LSCFB riser

Razzak, Shaikh A.; Agarwal, Kapil; Zhu, Jesse; Zhang, Chao

doi:10.1016/j.powtec.2008.03.016

Cited by 27 publications

(9 citation statements)

References 14 publications

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“…To optimize the products of the reactor, both excellent design and reasonable operation of the CFB, which are closely related to the gas-solids distribution, solids back-mixing, and residence time distribution, are critical. Extensive experiment and simulation studies focused on the gas-solids flow characteristics of CFB and found plenty of useful results such as solids holdup distribution, velocity distribution, solids back-mixing, and effects of both geometry and operating conditions [1][2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Comparison of Riser-Simplified, Riser-Only, and Full-Loop Simulations for a Circulating Fluidized Bed

Wang

Shi

et al. 2019

Processes

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With the development of computing power, the simulation of circulating fluidized bed (CFB) has developed from riser-simplified simulation to riser-only simulation, then to full-loop simulation. This paper compared these three methods based on pilot-scale CFB experiment data to find the scope of application of each method. All these simulations, using the Eulerian–Eulerian two-fluid model with the kinetic theory of granular theory, were conducted to simulate a pilot-scale CFB. The hydrodynamics, such as pressure balance, solids holdup distribution, solids velocity distribution, and instantaneous mass flow rates in the riser or CFB system, were investigated in different simulations. By comparing the results from different methods, it was found that riser-simplified simulation is not sufficient to obtain accurate hydrodynamics, especially in higher solids circulating rates. The riser-only simulation is able to make a reasonable prediction of time-averaged behaviors of gas–solids in most parts of riser but the entrance region. Further, the full-loop simulation can not only predict precise results, but also obtain comprehensive details and instantaneous information in the CFB system.

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Section: Introductionmentioning

confidence: 99%

Comparison of Riser-Simplified, Riser-Only, and Full-Loop Simulations for a Circulating Fluidized Bed

Wang

Shi

et al. 2019

Processes

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“…Shilapuram et al (2009Shilapuram et al ( , 2011, Shilapuram and Sai (2012) examined the macroscopic flow properties in LSCFBs by considering the effects of different operation methods, liquid viscosities and liquid distributors. By means of numerical modeling and investigation, the effects of other operating parameters such as G S and U L including primary and auxiliary liquid velocities were discussed by Razzak et al (2008Razzak et al ( , 2010 using CFD modeling. Roy et al (2014) proposed a modeling framework for the simulation of the hydrodynamic characteristics of LSCFBs by using CFD modeling and a cluster structure-dependent drag model was examined by Liu et al (2015).…”

Section: Liquid-solid Circulating Uidized Beds (Lscfbs)mentioning

confidence: 99%

Characteristics of Three-Phase (Gas–Liquid–Solid) Circulating Fluidized Beds

Kang

Kim²,

Yang

et al. 2018

Journal of Chemical Engineering of Japan

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The characteristics of three-phase (gas-liquid-solid) circulating uidized beds (TPCFBs) are discussed in order to visualize the unique features and advantages thereof due to the intrinsic ow and contacting behaviors of multi-phases, providing a better understanding of the state of art of TPCFBs and their feasible applications as multi-phase reactors and contactors. The hydrodynamics such as individual phase holdups, bubbling ow behaviors, bubble properties and liquid phase dispersions, and heat and mass transfer characteristics in the riser were examined based on the previous investigations. (k L a), gas-liquid interfacial area (a) and liquid side mass transfer coe cient (k L ) were determined. The information on the heat and mass transfer, however, were extremely limited comparing with those of hydrodynamics. Some correlations were suggested to predict the hydrodynamic parameters, and the values of h, k L a, a, and k L in the riser of the TPCFBs to provide insights for the present and future studies. The mechanism of heat and mass transfer and their modeling should be conducted for the better prediction of the performance of the TPCFB-reactors and contactors in the future. Although the information in the riser of various kinds of TPCFBs deviated from each other depending on the solid circulation modes and experimental conditions, they were summarized and consociated for the elucidation of the present states and views of the investigations. Rational guides to predict the hydrodynamics and heat and mass transfer phenomena in the riser of the TPCFB were possible by analyzing and synthesizing the results reported in the literatures presently available. Especially, the e ects of operating variables including gas (U G ) and liquid (U L ) velocities, properties of uidized solid particles and continuous liquid media, and solid circulation rate (Gs) on the hydrodynamic parameters and the heat and mass transfer characteristics such as heat transfer coe cient (h) and resistance, volumetric mass transfer coe cient

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“…No slip boundary condition for the liquid was used at the wall, whereas for the solids, a specularity coefficient was used at the wall. The value of specularity coefficient used was 0.01 [6]. The solids and the liquid exited the grid from the top where the outflow boundary condition was used.…”

Section: Simulationmentioning

confidence: 99%

“…This is so because a model parameter needs to be fitted to experimental data. Recent work on modelling the hydrodynamics of LSCFB [6] has been able to predict radial profiles of solids volume fraction, liquid velocity and solids velocity in the riser. The results are reported to compare favourably with experimental values.…”

Section: Introductionmentioning

confidence: 99%

Numerical Studies on Average Solids Holdup in a Liquid–Solid Circulating Fluidized Bed Riser

Voore

Roy

Sai

2012

Indian Chemical Engineer

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Computational fluid dynamic simulations were carried out to predict the radial profiles of solids volume fraction, liquid velocity and solids velocity. The effect of primary and auxiliary liquid velocities on average solids holdup in the riser was computed and the results were found to compare favourably with the experimental data. The effect of method of operation on average solids holdup in the riser was studied for three different methods of operations and the simulations were able to predict the average holdup values in close agreement with the experimental data. The effect of viscosity of the liquid on radial and axial profiles of solids holdup and average solids holdup in the column were studied and found to match well with experimental data. The effect of locations of the inlet of solids into the riser was also studied by comparing the radial profiles of solids volume fraction at different heights along the riser for various locations of solids inlet.

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Numerical investigation on the hydrodynamics of an LSCFB riser

Cited by 27 publications

References 14 publications

Comparison of Riser-Simplified, Riser-Only, and Full-Loop Simulations for a Circulating Fluidized Bed

Comparison of Riser-Simplified, Riser-Only, and Full-Loop Simulations for a Circulating Fluidized Bed

Characteristics of Three-Phase (Gas–Liquid–Solid) Circulating Fluidized Beds

Numerical Studies on Average Solids Holdup in a Liquid–Solid Circulating Fluidized Bed Riser

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