Modeling of fluidized bed reactors with two reaction zones

Gascón, Jorge; Téllez, Carlos; Herguido, J.; Jakobsen, Hugo A.; Menéndez, M.

doi:10.1002/aic.11002

Cited by 21 publications

(18 citation statements)

References 37 publications

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“…33,36 A change in the volume in the bubbles must be compensated by a net gas (or solid) flow from the emulsion to bubble and wake or vice versa. This is done as follows:…”

Section: Fluidized Bed Reactor Modelmentioning

confidence: 99%

Chemical‐looping combustion process: Kinetics and mathematical modeling

et al. 2010

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Chemical Looping Combustion technology involves circulating a metal oxide between a fuel zone where methane reacts under anaerobic conditions to produce a concentrated stream of CO 2 and water and an oxygen rich environment where the metal is reoxidized. Although the needs for electrical power generation drive the process to high temperatures, lower temperatures (600-800 C) are sufficient for industrial processes such as refineries. In this paper, we investigate the transient kinetics of NiO carriers in the temperature range of 600 to 900 C in both a fixed bed microreactor (WHSV ¼ 2-4 g CH 4 /h/g oxygen carrier) and a fluid bed reactor (WHSV ¼ 0.014-0.14 g CH 4 /h per g oxygen carrier). Complete methane conversion is achieved in the fluid bed for several minutes. In the microreactor, the methane conversion reaches a maximum after an initial induction period of less than 10 s. Both CO 2 and H 2 O yields are highest during this induction period. As the oxygen is consumed, methane conversion drops and both CO and H 2 yields increase, whereas the CO 2 and H 2 O concentrations decrease. The kinetics parameter of the gas-solids reactions (reduction of NiO with CH 4 , H 2 , and CO) together with catalytic reactions (methane reforming, methanation, shift, and gasification) were estimated using experimental data obtained on the fixed bed microreactor. Then, the kinetic expressions were combined with a detailed hydrodynamic model to successfully simulate the comportment of the fluidized bed reactor.

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“…33,36 A change in the volume in the bubbles must be compensated by a net gas (or solid) flow from the emulsion to bubble and wake or vice versa. This is done as follows:…”

Section: Fluidized Bed Reactor Modelmentioning

confidence: 99%

Chemical‐looping combustion process: Kinetics and mathematical modeling

et al. 2010

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“…The source terms in the solid phase were based on the kinetic model of Jackson and Stitt 16 for propane dehydrogenation over Cr 2 O 3 /Al 2 O catalyst. To simplify the model we neglected the reactions for the formation of C 2 side products, and included the main propene reaction and the two reactions that produced coke:…”

Section: Pdh Operating Conditions and Settingsmentioning

confidence: 99%

“…15 Further difficulties are the highly endothermic nature of the reaction, and the equilibrium limitations that require operation at high temperatures (800-950 K) and at pressure close to atmospheric. Some novel concepts to manage both the deactivation and the thermal problems include the use of a two-zone fluidized bed, 16 membrane reactors, 17 a rotating monolith reactor, 18 and reverse flow reactors. 19,20 To date, the economic and practical problems raised by these more sophisticated designs have prevented their commercial implementation.…”

Section: Introductionmentioning

confidence: 99%

Catalyst Deactivation in 3D CFD Resolved Particle Simulations of Propane Dehydrogenation

Behnam

Dixon

Nijemeisland

et al. 2010

Ind. Eng. Chem. Res.

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Catalyst deactivation by carbon deposition has been investigated for the dehydrogenation of propane to propene on a Cr 2 O 3 /Al 2 O 3 catalyst. Computational fluid dynamics was used to couple the 3D transport and reaction processes occurring inside the cylindrical pellet to the gas flow around the pellet. The pellet scale reaction and carbon laydown are shown to be strongly affected by the bed scale tube wall heat flux supplied for the endothermic reactions, and the species distributions on the pellet surface are also affected by the ease of reactant access to the particle. The development of particle internal gradients and carbon accumulation are illustrated for the early stages of deactivation. Carbon deposition is initially strongest in the high temperature regions close to the tube wall. As time progresses, the increased deactivation caused by the carbon acts to reduce all rates of reaction, and propene production and coke formation shift to other regions of the pellet.

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“…O 2 -butane mixtures are passed through the catalyst bed at elevated temperatures, and the resulting products are separated or analyzed. Modeling of fluidized-bed reactors with recirculation of the catalyst is important in improving the overall processing technology for selective oxidation of n-butane (226,(231)(232)(233)(234)(235). Chief among these are the safety limitations imposed by the explosive limits of mixtures of butane and O 2 /air.…”

Section: Reactor Technology For N-butane Oxidationmentioning

confidence: 99%

“…These applications are mainly in selective oxidation (3,73,87,90-94, 96-102,154,195,208,237,251-269), ammoxidation (88)(89)(90)270), dehydrogenation (232,(271)(272)(273)(274)(275)(276), and dehydration (277,278). These applications are mainly in selective oxidation (3,73,87,90-94, 96-102,154,195,208,237,251-269), ammoxidation (88)(89)(90)270), dehydrogenation (232,(271)(272)(273)(274)(275)(276), and dehydration (277,278).…”

Section: Wider Application Of Vanadium Phosphate Catalystsmentioning

confidence: 99%