Modeling flow and residence time distribution in an industrial-scale reactor with a plunging jet inlet and optional agitation

Bai, Hua; Stephenson, Amber L.; Jimenez, Jorge; Jewell, Dennis E.; Gillis, Paul

doi:10.1016/j.cherd.2008.08.012

Cited by 20 publications

(19 citation statements)

References 8 publications

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“…Two main methods are used: -Particle tracking (Castelain et al, 2000;Sahle-Demessie et al, 2003;Le Moullec et al, 2008;Bai et al, 2008;Aubin et al, 2009;Habchi et al, 2010): this method is based on the simulation of the transport of Lagrangian particles injected at the reactor inlet at a given time (pulse injection). The trajectory of the particles obeys the force balance.…”

Section: Methodsmentioning

confidence: 99%

“…The disadvantage of this method is that the tracer is not submitted to molecular diffusion. With a no-slip boundary condition at the reactor walls, particles injected near the walls may leave the reactor after a very long time, notably in laminar flow (Castelain et al, 2000;Bai et al, 2008;Aubin et al, 2009). In real flow conditions, the tracer at the wall would have been tangentially transported towards the reactor core by molecular diffusion.…”

Section: Methodsmentioning

confidence: 99%

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A new numerical method for axial dispersion characterization in microreactors

Moreau¹,

Raimondi²,

Sauze³

et al. 2017

Chemical Engineering Science

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new numerical method for axial dispersion characterization in microreactors.(2017) Chemical Engineering Science, vol. 168. pp. 178-188. ISSN 0009-2509 Open Archive TOULOUSE Archive Ouverte (OATAO) OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. h i g h l i g h t sAn innovative numerical method for axial dispersion characterization is proposed. The method is validated thanks to a RTD experiment in a microchannel. The method is applied to rectangular millimetric wavy channels. The impact of the channel geometry on the axial dispersion coefficient is studied. Keywords:Axial dispersion Numerical method CFD simulations Microreactor Wavy channel a s t r a c t Axial dispersion is a key phenomenon in reactor engineering that can affect yield and selectivity when reactions are carried out. Therefore its characterization is necessary for an adequate modelling of the reactor. The development of compact reactors to fit with process intensification expectations requires the use of characterization methods adapted to small-scale devices. An original method not-frequently used up to now for the estimation of axial dispersion coefficients is presented and applied to millimetric wavy channels. It is based on CFD simulations to calculate velocity and concentration fields from which axial dispersion coefficient can be estimated. This method is used to predict the impact of the wavy channel geometry and of the fluid velocity on axial dispersion in laminar flow regime. The investigated geometrical parameters are the hydraulic diameter (2-4 mm), the cross-sectional aspect ratio defined as the ratio between the channel width and its depth (0.25-1) and the internal curvature radius of the bends (2-3.4 mm). The range of Reynolds number considered is Re = 70-1 600. Axial dispersion coefficient increases with velocity, values range from 2.8 Á 10 À4 to 3.2 Á 10 À3 m 2 Ás À1. It appears that axial dispersion varies slightly in function of the channel hydraulic diameter. Square wavy channels generate less axial dispersion than rectangular wavy ones. Finally, axial dispersion coefficient increases with the internal curvature radius which shows the positive impact of sharp bends to reduce axial dispersion effect.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

A new numerical method for axial dispersion characterization in microreactors

Moreau¹,

Raimondi²,

Sauze³

et al. 2017

Chemical Engineering Science

View full text Add to dashboard Cite

show abstract

“…They consist of a strong primary loop in the impeller discharge region and a smaller secondary loop below the impeller. Usually, the flow field generated by down-pumping multiple impellers with large values of impeller separation (also known as S/H values) is such that the downward discharge and circulation loops are well defined for each impeller as in studies conducted by [25] [26]. However, in the present study, it is observed that the loops are more pronounced in the discharge region of the lower impeller.…”

Section: Resultsmentioning

confidence: 46%

Determination of Flow Structure in a Gold Leaching Tank by CFD Simulation

Dagadu¹,

Stęgowski²,

Furman³

et al. 2014

JAMP

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Experimental residence time distribution (RTD) measurement and computational fluid dynamics (CFD) simulation are the best methods to study the hydrodynamics of process flow systems. However, CFD approach leads to better understanding of the flow structure and extent of mixing in stirred tanks. In the present study, CFD models were used to simulate the flow in an industrial gold leaching tank. The objective of the investigation was to characterize the flowfield generated within the tank after process intensification. The flow was simulated using an Eulerian-Eulerian multi-fluid model where the RANS standard -ε mixture model and a multiple reference frame approach were used to model turbulence and impeller rotation respectively. The simulated flowfield was found to be in agreement with the flow pattern of pitched blade axial-flow impellers that was used for mixing. The leaching tank exhibited good "off-bottom suspension" which reveals minimum deposition of gold ore particles on the bottom of the leaching tanks. Simulation results were consistent with experimental results obtained from a radioactive tracer investigation. CFD approach gave a better description of the flow structure and extent of mixing in a leaching tank. Hence it could be a preferred approach for flow system analysis where the cost of experimentation is high.

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“…Another approach is to use Computational Fluid Dynamics (CFD) to obtain simulated RTD and then using this RTD reactor performance is predicted. Inappropriate RTD sampling and numerical diffusions can lead to significant deviations in the RTD predictions using CFD [4]. Advances in CFD and precision in measurements have improved the knowledge of the flow fields in the reactors.…”

Section: Introductionmentioning

confidence: 99%

Numerical Testing and Validation of a Model for Laminar Flow Tubular Reactor

Kallur¹,

Raj²

2014

IJIRSET

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Non-ideality in the reactors is accounted traditionally using Residence Time Distribution (RTD) studies. However RTD studies are conducted on existing reactors. Therefore accounting for non-ideality at the design stage using RTD is not possible. There are several causes of non-ideality in the reactors. The non-ideality in Laminar Flow Tubular Reactor (LFTR) is due to variation in velocity in the radial direction, diffusion and convection effects of reacting and product species. One peculiar feature of LFTR is the non-ideality due to radial variation in velocity is mathematically deterministic. There is no work reported in the literature that makes use of this deterministic nature of non-ideality except some analytical methods for simple kinetics. The present paper deals with simple mathematical model that makes use of theoretical RTD of LFTR to predict the reactor performance for general kinetics by a numerical method. Testing and validation of the model is done for kinetics for which analytical solutions are not available. Algorithm for numerical testing is developed. The algorithm is used to develop computer code which is used to predict reactor performance and testing. The reactor performances predicted are compared with already well established methods. The results agree well.

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Modeling flow and residence time distribution in an industrial-scale reactor with a plunging jet inlet and optional agitation

Cited by 20 publications

References 8 publications

A new numerical method for axial dispersion characterization in microreactors

A new numerical method for axial dispersion characterization in microreactors

Determination of Flow Structure in a Gold Leaching Tank by CFD Simulation

Numerical Testing and Validation of a Model for Laminar Flow Tubular Reactor

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