Characterization of the flow pattern in a downer reactor

Lehner, Peter; Wirth, Karl‐Ernst

doi:10.1016/s0009-2509(99)00286-9

Cited by 55 publications

(17 citation statements)

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“…In addition, the system pressure drop relates to the K 2 CO 3 solid sorbent volume fraction. The vertical pressure gradient is a direct measurement of the cross‐sectional average solid volume fraction 35, 36. The system pressure drop profile decreases along the riser height owing to the decreasing of K 2 CO 3 solid sorbents.…”

Section: Resultsmentioning

confidence: 99%

A computational fluid dynamics design of a carbon dioxide sorption circulating fluidized bed

2010

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A kinetic theory based hydrodynamic model with experimentally determined sorption rates for reaction of CO 2 with K 2 CO 3 solid sorbent is used to design a compact circulating fluidized bed sorption-regeneration system for CO 2 removal from flue gases. Because of high solids fluxes, the sorber does not require internal or external cooling. The output is verified by computing the granular temperatures, particle viscosities, dispersion, and mass transfer coefficients. These properties agree with reported measurement values except the radial dispersion coefficients, which are much higher due to the larger bed diameter. With the solid sorbent prepared according to published information, the CO 2 removal percentage at the riser top is 69.16%. To improve the CO 2 removal, an effort is needed to develop a better sorbent or to simply lower the inlet gas velocity to operate in a denser mode, leading to a larger system. Also, the effect of temperature rise on the removal efficiency is investigated.

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Section: Resultsmentioning

confidence: 99%

A computational fluid dynamics design of a carbon dioxide sorption circulating fluidized bed

2010

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“…The hydrodynamics study [1][2][3][4][5][6] shows that the radial distribution of flow parameters such as particle velocity, gas velocity and solids concentration in the downer is more uniform than in the riser, and it was also stated that the radial flow structure does not result in severe radial non-uniformity even in a fast reaction like fluid catalytic cracking (FCC) [7]. Therefore, the importance of the axial flow structure becomes very significant.…”

Section: Introductionmentioning

confidence: 99%

Axial flow structure at the varying superficial gas velocity in a downer reactor

Deng

Liu

Wei

et al. 2004

Chemical Engineering Journal

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“…Compared with the up-flow fast fluidized bed riser, downer reactors of fluidized bed have many advantages such as good gas-solids contact, less gas and solids back-mixing, a short contact time and more uniform residence time distribution. (Srivastava et al 1998;Lehner and Wirth 1999;Cheng et al 1999;Liu et al 2001;Li et al 2004;Lu and Gidaspow 2003;Lu et al 2005;Luo et al 2007;Wu et al 2008;He et al 2009a, b). Computational fluid dynamics (CFD) with an Euler-Euler two-fluid modeling approaches has been widely used to predict hydrodynamics in circulated fluidized bed.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic Modeling of Dense Gas-Particle Turbulence Flows Under Microgravity Space Environments

Liu

Kallio

2010

Microgravity Sci. Technol.

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An Euler-Euler two-fluid model based on the second-order-moment closure approach and the granular kinetic theory of dense gas-particle flows was presented. Anisotropy of gas-solid two-phase stress and the interaction between two-phase stresses are fully considered by two-phase Reynolds stress model and the transport equation of two-phase stress correlation. Under the microgravity space environments, hydrodynamic characters and particle dispersion behaviors of dense gas-particle turbulence flows are numerically simulated. Simulation results of particle concentration and particle velocity are in good agreement with measurement data under earth gravity environment. Decreased gravity can decrease the particle dispersion and can weaken the particle-particle collision as well as it is in favor of producing isotropic flow structures. Moreover, axial-axial fluctuation velocity correlation of gas and particle in earth gravity is approximately 3.0 times greater than those of microgravity and it is smaller than axial particle velocity fluctuation due to larger particle inertia and the larger particle turbulence diffusions.Y. Liu (B) Marine Engineering College,

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Characterization of the flow pattern in a downer reactor

Cited by 55 publications

References 0 publications

A computational fluid dynamics design of a carbon dioxide sorption circulating fluidized bed

A computational fluid dynamics design of a carbon dioxide sorption circulating fluidized bed

Axial flow structure at the varying superficial gas velocity in a downer reactor

Hydrodynamic Modeling of Dense Gas-Particle Turbulence Flows Under Microgravity Space Environments

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