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

Kashyap, Mayank; Gidaspow, Dimitri

doi:10.1002/aic.12615

Cited by 18 publications

(15 citation statements)

References 44 publications

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“…Otherwise, by assuming a homogeneous system, e.g., ideal plug flow, overestimation of the conversion rate in heterogeneous systems is likely to result. The contact efficiency could be determined by assuming a riser as a steady-state plug flow reactor: 24 , 25 , 48 , 50 , 63 with a solution: where s is the averaged solids volume fraction in a slice of thickness Δz , U the gas superficial velocity, K ov the apparent volumetric reaction rate constant, γ pf a gas–solid contact efficiency, and Da the Damköhler number defined as The gas–solid contact efficiency γ pf could be computed at different axial increments of Δz , by quantifying the contact efficiency as the ratio between the apparent conversion rate and the conversion obtained when a 1D plug flow model is assumed, ignoring any heterogeneity.…”

Section: Methodsmentioning

confidence: 99%

“… 45 Some of these computational studies have suggested that global scale mass-transfer resistances are related to cluster formation. 20 , 25 , 46 However, these findings are not explicitly supported with cluster scale level computations, such as the instantaneous gas–solid contact efficiency of particle clusters.…”

Section: Introductionmentioning

confidence: 91%

“… 20 , 21 Larger (than particle level) scale hydrodynamic resistances can play an important role in mass-transfer phenomena. 22 − 25 …”

Section: Introductionmentioning

confidence: 99%

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Computational Fluid Dynamics–Discrete Element Method (CFD-DEM) Study of Mass-Transfer Mechanisms in Riser Flow

Varas

Peters

Kuipers

2017

Ind. Eng. Chem. Res.

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We report a computational fluid dynamics–discrete element method (CFD-DEM) simulation study on the interplay between mass transfer and a heterogeneous catalyzed chemical reaction in cocurrent gas-particle flows as encountered in risers. Slip velocity, axial gas dispersion, gas bypassing, and particle mixing phenomena have been evaluated under riser flow conditions to study the complex system behavior in detail. The most important factors are found to be directly related to particle cluster formation. Low air-to-solids flux ratios lead to more heterogeneous systems, where the cluster formation is more pronounced and mass transfer more influenced. Falling clusters can be partially circumvented by the gas phase, which therefore does not fully interact with the cluster particles, leading to poor gas–solid contact efficiencies. Cluster gas–solid contact efficiencies are quantified at several gas superficial velocities, reaction rates, and dilution factors in order to gain more insight regarding the influence of clustering phenomena on the performance of riser reactors.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 91%

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Computational Fluid Dynamics–Discrete Element Method (CFD-DEM) Study of Mass-Transfer Mechanisms in Riser Flow

Varas

Peters

Kuipers

2017

Ind. Eng. Chem. Res.

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“…[31][32][33] Their main difference compared with the fluidized beds 34 is that solid particles are fixed in the reactor. Thus, it is difficult to describe fluid flow in detail among packed particles because of the complex geometrical structure.…”

Section: Discussionmentioning

confidence: 99%

Optimization and simulation of the Sabatier reaction process in a packed bed

et al. 2016

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The Sabatier reaction in a testing packed bed was investigated experimentally and theoretically, and was used to convert waste carbon dioxide and hydrogen to provide needed water for closing the life-support loop on orbit in space. A three-dimensional model including fluid flow, gas dispersion, heat and mass transfer, and chemical reaction was developed by coupling some semi-empirical correlated equations in chemical engineering science into computational fluid dynamics theory. Good agreements between the simulating results and experimental data for the effect of some parameters on reaction verified this model, for example, heat exchange between reactor and atmosphere, the material property of reactor, the catalyst deactivated and gas mass flux and so on. By using this model as the designing tools, an optimized packed bed is proposed. Compared with the testing packed bed, the relevant reactor length can be reduced from 220 to 150 mm with the same hydrogen conversion and lower pressure drop. V C 2016 American Institute of Chemical Engineers AIChE J, 00: 000-000, 2016

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

Cited by 18 publications

References 44 publications

Computational Fluid Dynamics–Discrete Element Method (CFD-DEM) Study of Mass-Transfer Mechanisms in Riser Flow

Computational Fluid Dynamics–Discrete Element Method (CFD-DEM) Study of Mass-Transfer Mechanisms in Riser Flow

Optimization and simulation of the Sabatier reaction process in a packed bed

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

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

Cited by 18 publications

References 44 publications

Computational Fluid Dynamics–Discrete Element Method (CFD-DEM) Study of Mass-Transfer Mechanisms in Riser Flow

Computational Fluid Dynamics–Discrete Element Method (CFD-DEM) Study of Mass-Transfer Mechanisms in Riser Flow

Optimization and simulation of the Sabatier reaction process in a packed bed

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

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Product

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