The effect of particle size distribution on the performance of a catalytic fluidized bed reactor

Sun, Guikai; Grace, John R.

doi:10.1016/0009-2509(90)80094-u

Cited by 82 publications

(41 citation statements)

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“…For all the distributions investigated, the FINAL TECHNICAL REPORT 134 experimental pressure drops (data points) plateau at the measured bed weight (W) divided by the cross-sectional area (A) (horizontal dashed line), indicating that the bed was completely fluidized beyond U cf . As expected, U cf values are similar, because the distributions are centered about the same mean particle size (d sm ); it has been reported that U cf values of the continuous distributions agree with U mf of the mean particle size (Sun and Grace, 1990;. Notably, the U cf value of the widest distribution investigation, specifically lognormal distribution with σ/d sm = 70%, is slightly higher than the other distributions, presumably due to the presence of the largest amount of coarse Group D particles.…”

Section: Figure 103 Evolution Of Granular Temperature With Differentsupporting

confidence: 55%

“…A brief review of species segregation experiments and simulations in bubbling fluidized beds with binary mixtures has been presented by Joseph et al . Comparatively, few efforts have been devoted to the investigation of continuous size distributions; these previous contributions are described below.Experimental results have been presented on the impact of continuous size distributions on the fluid mechanical behavior of bubbling beds, with effects ranging from minimum fluidization velocity (Sun and Grace 1990;Lin, Wey et al 2002), bubble sizes (Beetstra, Nijenhuis et al 2009), pressure fluctuations(Grace and Sun 1991), presence of particles in bubbles(Sun and Grace 1990; Sun and Grace 1994), etc. The contribution by Grace and Sun(Grace and Sun 1991) represents one of the earliest reviews on the influence of particle size distribution (PSD) on the quality of fluidization, and they summarized that a wider PSD (of Geldart Group A particles) culminates in enhanced reactor efficiency through improved interphase mass transfer and better gas-solid contacting.…”

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confidence: 99%

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Development, Verification, and Validation of Multiphase Models for Polydisperse Flows

Hrenya¹,

Cocco²,

Fox³

et al. 2011

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This report describes in detail the technical findings of the DOE Award entitled "Development, Verification, and Validation of Multiphase Models for Polydisperse Flows." The focus was on high-velocity, gas-solid flows with a range of particle sizes. A complete mathematical model was developed based on first principles and incorporated into MFIX. The solid-phase description took two forms: the Kinetic Theory of Granular Flows (KTGF) and Discrete Quadrature Method of Moments (DQMOM). The gas-solid drag law for polydisperse flows was developed over a range of flow conditions using Discrete Numerical Simulations (DNS). These models were verified via examination of a range of limiting cases and comparison with Discrete Element Method (DEM) data. Validation took the form of comparison with both DEM and experimental data. Experiments were conducted in three separate circulating fluidized beds (CFB's), with emphasis on the riser section. Measurements included bulk quantities like pressure drop and elutriation, as well as axial and radial measurements of bubble characteristics, cluster characteristics, solids flux, and differential pressure drops (axial only). Monodisperse systems were compared to their binary and continuous particle size distribution (PSD) counterparts. The continuous distributions examined included Gaussian, lognormal, and NETLprovided data for a coal gasifier.FINAL TECHNICAL 4 DE-FC26-07NT43098 5 EXECUTIVE SUMMARYThis report is the final technical report for the award DE-FC26-07NT43098 entitled "Development, Verification, and Validation of Multiphase Models for Polydisperse Flows." Below is a summary of work completed under the grant for each of the major goals. Goal I: Continuum Theory for Solid PhaseTwo separate and complementary continuum theories were derived to model polydisperse solids: the kinetic theory of granular flow (KTGF) and the discrete quadrature method of moments (DQMOM). Both theories are based on first principles with no adjustable parameters. The polydisperse KTGF and DQMOM were then encoded in MFIX, and underwent a wide range of verification testing to ensure, to the best possible extent, that no coding errors were present. These verification tests included both granular and gas-solid flows, including cases where an analytical solution and/or DEM (discrete element method) data and/or simple test cases. For the case of KTGF, another set of constitutive equations were derived which rigorously incorporated the gas phase for a simplified case of monodisperse systems at low Reynolds numbers. This derivation used the acceleration model developed in Task 2 from direct numerical simulations (DNS) in the starting kinetic equation, and indicated the effect of the fluid phase on the resulting constitutive relations. Goal II: Improved Gas-Particle Drag Laws -effect of particle size distributionIn this portion of the effort, two types of direct numerical simulations (DNS) were used to extract the drag force experienced by particles in a polydisperse suspension. These two methods, na...

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Section: Figure 103 Evolution Of Granular Temperature With Differentsupporting

confidence: 55%

mentioning

confidence: 99%

Development, Verification, and Validation of Multiphase Models for Polydisperse Flows

Hrenya¹,

Cocco²,

Fox³

et al. 2011

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“…The ozone decomposition reaction was implemented to gauge the FBR's reactor performance. This reaction is popular in FBR experiments due to its first order nature and the small quantities required for analysis resulting in negligible volume change and heat generation [1,15,28,34]. A third packed bed test reactor, with ideal plug flow behaviour and no hydrodynamic influences, was used solely to determine the first order rate constant of the catalyst being utilized in the FBR reaction setup.…”

Section: Methodsmentioning

confidence: 99%

“…In this low U 0 /U c regime the bubbles have nearideal geometries and low interactions with each other. Despite the success of these models at lower velocities, the transfer correlations are not suited for higher velocity operations [25,[27][28][29].…”

Section: Introductionmentioning

confidence: 99%

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Interphase mass transfer of the high velocity bubbling fluidization regime

Saayman

Nicol

2015

Chemical Engineering Research and Design

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Gas-solid fluidization experiments were performed in two separate experimental setups with similar dimensions. Fast X-Ray Tomography (XRT) was used in setup 1, while ozone decomposition experiments were performed in setup 2. Packing and operation characteristics for the two setups were close to identical. The hydrodynamic measurements from the XRT acquisitions were used to evaluate the interphase mass transfer characteristics obtained from the ozone decomposition results. Superficial velocities (U 0 ) spanning the bubbling up to the onset of the turbulent regime (U c ) were employed. Traditional specific interphase mass transfer (k be ) correlations are based on incipiently fluidized beds; however, results suggested that a distinction should be made between the low-interaction bubbling regime and the highinteraction bubbling regime. A change in mass transfer behaviour occurred around a U 0 /U c value of 0.25. An empirical correlation for k be of the high-interaction bubbling regime is 1

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Fluidized‐bed catalytic reactors

Grace

2016

Multiphase Catalytic Reactors

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The effect of particle size distribution on the performance of a catalytic fluidized bed reactor

Cited by 82 publications

References 4 publications

Development, Verification, and Validation of Multiphase Models for Polydisperse Flows

Development, Verification, and Validation of Multiphase Models for Polydisperse Flows

Interphase mass transfer of the high velocity bubbling fluidization regime

Fluidized‐bed catalytic reactors

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