Computation and measurements of mass transfer and dispersion coefficients in fluidized beds

Kashyap, Mayank; Gidaspow, Dimitri

doi:10.1016/j.powtec.2010.03.025

Cited by 38 publications

(29 citation statements)

References 46 publications

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“…Among other reactions, the ozone decomposition reaction has been utilized by various authors4, 5, 9–19 as the chemical reaction for studying reactions in fluidized beds. A recent publication (Kashyap and Gidaspow20) described the use of ozone decomposition reaction in two different fluidized bed systems. It has been shown in the literature (Frye et al,21 Fryer and Potter,9 Jiang et al,22 Pagliolico et al,23 Ouyang et al,10, 11 and Hansen et al15) that the ozone decomposition reaction is a simple irreversible first order catalytic reaction, given as: where, 2 mols of ozone gas are converted to 3 mols of oxygen gas.…”

Section: Ozone Decomposition Reactionmentioning

confidence: 99%

“…The conservation of species equation for ozone, upon integration of Eq. 9 over time and over the radial ( x ‐axis) and tangential ( z ‐axis) directions, gave the 1‐D steady state balance as5, 20: where, v y was the velocity of gas phase in the axial ( y ‐axis) direction; Y was the axial ( y ‐axis) distance.…”

Section: Calculation Of Mass Transfer Coefficient and Sherwood Numbermentioning

confidence: 99%

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Measurements and computation of low mass transfer coefficients for FCC particles with ozone decomposition reaction

Kashyap

Gidaspow

2011

AIChE Journal

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in Wiley Online Library (wileyonlinelibrary.com).The mass transfer coefficients and Sherwood numbers for catalyzed fluid cracking catalyst particles were measured and computed in a two-dimensional (2-D) bubbling fluidized bed, with ozone decomposition reaction. The measured and computed Sherwood numbers, using 3-and 2-D kinetic theory based computational fluid dynamics simulations, were of the order of 10 À6 -10 À2. The low Sherwood numbers were in reasonable agreement with the literature data for small particles, at low Reynolds numbers. The computational fluid dynamics simulations showed that it is possible to compute conversions in fluidized bed reactors without using the conventional model with empirical mass transfer coefficients.

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Section: Ozone Decomposition Reactionmentioning

confidence: 99%

Section: Calculation Of Mass Transfer Coefficient and Sherwood Numbermentioning

confidence: 99%

Measurements and computation of low mass transfer coefficients for FCC particles with ozone decomposition reaction

Kashyap

Gidaspow

2011

AIChE Journal

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“…They found that simulation results with the assumption of homogeneous flows overestimated the interphase mass transfer rate. Kashyap and Gidaspow revealed that the effective interphase mass‐transfer coefficient would be several orders of magnitude smaller than the microscopic rate. Agrawal et al developed a filtered subgrid model for heat transfer in gas–solid flows based on fine‐grid TFM simulations in a 2D periodic domain.…”

Section: Introductionmentioning

confidence: 99%

Development of a filtered interphase heat transfer model based on fine‐grid simulations of gas–solid flows

et al. 2019

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The filtered interphase heat-transfer coefficient for coarse-grid simulations of gas-solid flows can be obtained via a correction (Q) to its microscopic counterpart. The numerical results show that a good linear correlation between Q and the subgrid drift temperature exists at various filtered solid volume fractions, filter sizes and Reynolds numbers, where the subgrid drift temperature is the correlation between the fluctuating temperature of the gas phase and the fluctuation of the gas volume fraction. Since Q can be determined solely by one subgrid quantity, closure for Q is directly pursued. It is found that Q correlates surprisingly well with the product of the filtered solid volume fraction and the filtered temperature difference between the two phases normalized by the filtered heat transfer at a larger scale than the considered coarse grid. A fitting correlation is formulated based on this observation, and its predictability is evaluated in an a priori test.

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“…In 1988, the explanation of the velocity distribution in a large riser diameter used in EXXON Company and the small riser used in the IIT laboratory was an initial step to modernize the method for multiphase CFD codes to design fluidized bed reactors with reasonable confidence to flow regimes. For fluidized bed reactor design, Breault, Chalermsinsuwan et al, Kashyap and Gidaspow and others explained the 50‐year‐old puzzle of the low Sherwood and Nusselt numbers in fluidized beds. They are below the theoretical limit of two due to the formation of particle clusters in risers.…”

Section: Introductionmentioning

confidence: 99%

CO₂ capture in a multistage CFB: Part I: Number of stages

et al. 2017

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The most common technology for postcombustion of CO 2 capture is the amine solvent scrubber. The energy consumption for capturing CO 2 from flue gases using amine solvent technology is 15-30% of the power plant electricity production. Hence, there is a need to develop more efficient methods of removing CO 2 . A circulating fluidized bed using sodium or potassium carbonates is potentially such a process, as their high decomposition pressures allow regeneration at low temperatures using waste heat rather than steam from the power plant. But equilibrium data for the sorbents require the use of several cooled stages to achieve high CO 2 conversions. Here, a method of computing such a number of stages for a given CO 2 conversion was developed using multiphase computational fluid dynamics. It was found that it required six equilibrium stages to remove 96% of CO 2 with the initial mole fraction of 0.15 in a sorption riser. V C 2017 American Institute of Chemical Engineers AIChE J, 63: 5267-5279, 2017 CO 2 capture conceptsState of the art of CO 2 capture technologies for existing fossil energy power plants are limited to amine absorbers. 16 They have been used for removal of CO 2 from natural gas for Correspondence concerning this article should be addressed to P. Piumsomboon at pornpote.p@chula.ac.th. Figure 6. Grid selection and simulation validation.(a) Grid selection study. (b) Comparison to the experiments. 39 [Color figure can be viewed at wileyonlinelibrary.com] 5272 Figure 13. Transient CO 2 capture.(a) Removal percent of CO 2. (b) Thermal sensitivity to CO 2 sorption. [Color figure can be viewed at wileyonlinelibrary.com] 5276

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Computation and measurements of mass transfer and dispersion coefficients in fluidized beds

Cited by 38 publications

References 46 publications

Measurements and computation of low mass transfer coefficients for FCC particles with ozone decomposition reaction

Measurements and computation of low mass transfer coefficients for FCC particles with ozone decomposition reaction

Development of a filtered interphase heat transfer model based on fine‐grid simulations of gas–solid flows

CO₂ capture in a multistage CFB: Part I: Number of stages

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Computation and measurements of mass transfer and dispersion coefficients in fluidized beds

Cited by 38 publications

References 46 publications

Measurements and computation of low mass transfer coefficients for FCC particles with ozone decomposition reaction

Measurements and computation of low mass transfer coefficients for FCC particles with ozone decomposition reaction

Development of a filtered interphase heat transfer model based on fine‐grid simulations of gas–solid flows

CO2 capture in a multistage CFB: Part I: Number of stages

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CO₂ capture in a multistage CFB: Part I: Number of stages