A factorial approach to understanding the effect of inner geometry of baffled meso-scale tubes on solids suspension and axial dispersion in continuous, oscillatory liquid-solid plug flows

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Abstract

Oscillatory flow reactors (OFRs) are a new generation of tubular mixing and reaction equipment uniquely capable of combining continuous near plug flow with homogeneous particle suspension, yet the design of OFRs for liquid-solid and multi-phase flow processes relies on rules established during the past two decades from single, liquid-phase studies. A Design of Experiment (DoE) approach was herein implemented for establishing the relationship between four key geometrical parameters of the inner tube baffles and both the suspension of particles and the axial dispersion for liquid-solid continuous flows in 10 mm internal diameter (d) meso-scale tubes with periodic baffles. The parameters evaluated were the orifice open diameter, do = 0.35d–0.50d; the open cross section, α = 0.12d–0.25d, constriction spacing, l = 1.5d–3.0d, and baffle shape (sharp vs smooth edged). A total of ten tubes were tested, five consisting of smooth periodic constrictions (SPC) and the other five of sharp edged periodic constrictions (SEPC) according to a complete 2×2 factorial design with 1 central point. Each tube was experimentally evaluated via optical imaging of suspended monodispersed polyvinyl chloride (PVC) particles. Both SPC and SEPC meso-tubes were capable of delivering a near plug behaviour and the values of axial dispersion coefficient (Dc) estimated for the solids were in the range of 1.0–2.2×10-4 m2 s-1. In contrast, the minimum (critical) fluid oscillation conditions required for full suspension of particles varied significantly, in general with the SPC tubes requiring up to 50% lower amplitude for full particles suspension. Overall, α revealed the dominant parameter in controlling solids backmixing and, and the inner tube geometry requiring the lowest energy input for homogenous particle suspension and minimum Dc (i.e. sharpest residence time distribution) presented a l/d = 3, do = 0.35d, α = 12% and SPC design. This study is believed to support the future design of optimised meso-scale OFR systems for continuous screening and manufacturing of value-added liquid-solid and multi-phase systems, such as catalytic and crystallisation processes.
LanguageEnglish
Pages669–682
Number of pages14
JournalChemical Engineering Journal
Volume308
Early online date6 Sep 2016
DOIs
Publication statusPublished - 15 Jan 2017

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Suspensions
geometry
oscillating flow
liquid
Geometry
Liquids
Residence time distribution
Multiphase flow
Orifices
Crystallization
Polyvinyl Chloride
Polyvinyl chlorides
Design of experiments
multiphase flow
Screening
effect
particle
residence time
spacing
crystallization

Keywords

  • oscillatory flow
  • meso-scale reactor
  • smooth periodic constrictions
  • design of experiments
  • solid-liquid flow
  • plug flow
  • OFRs

Cite this

@article{dd8e9bc69e2040db94f5afc35113d1d3,
title = "A factorial approach to understanding the effect of inner geometry of baffled meso-scale tubes on solids suspension and axial dispersion in continuous, oscillatory liquid-solid plug flows",
abstract = "Oscillatory flow reactors (OFRs) are a new generation of tubular mixing and reaction equipment uniquely capable of combining continuous near plug flow with homogeneous particle suspension, yet the design of OFRs for liquid-solid and multi-phase flow processes relies on rules established during the past two decades from single, liquid-phase studies. A Design of Experiment (DoE) approach was herein implemented for establishing the relationship between four key geometrical parameters of the inner tube baffles and both the suspension of particles and the axial dispersion for liquid-solid continuous flows in 10 mm internal diameter (d) meso-scale tubes with periodic baffles. The parameters evaluated were the orifice open diameter, do = 0.35d–0.50d; the open cross section, α = 0.12d–0.25d, constriction spacing, l = 1.5d–3.0d, and baffle shape (sharp vs smooth edged). A total of ten tubes were tested, five consisting of smooth periodic constrictions (SPC) and the other five of sharp edged periodic constrictions (SEPC) according to a complete 2×2 factorial design with 1 central point. Each tube was experimentally evaluated via optical imaging of suspended monodispersed polyvinyl chloride (PVC) particles. Both SPC and SEPC meso-tubes were capable of delivering a near plug behaviour and the values of axial dispersion coefficient (Dc) estimated for the solids were in the range of 1.0–2.2×10-4 m2 s-1. In contrast, the minimum (critical) fluid oscillation conditions required for full suspension of particles varied significantly, in general with the SPC tubes requiring up to 50{\%} lower amplitude for full particles suspension. Overall, α revealed the dominant parameter in controlling solids backmixing and, and the inner tube geometry requiring the lowest energy input for homogenous particle suspension and minimum Dc (i.e. sharpest residence time distribution) presented a l/d = 3, do = 0.35d, α = 12{\%} and SPC design. This study is believed to support the future design of optimised meso-scale OFR systems for continuous screening and manufacturing of value-added liquid-solid and multi-phase systems, such as catalytic and crystallisation processes.",
keywords = "oscillatory flow, meso-scale reactor, smooth periodic constrictions, design of experiments, solid-liquid flow, plug flow, OFRs",
author = "Ejim, {Louisa N.} and Stephanie Yerdelen and Thomas McGlone and I Onyemelukwe and Blair Johnston and Florence, {Alastair J.} and Reis, {Nuno M.}",
year = "2017",
month = "1",
day = "15",
doi = "10.1016/j.cej.2016.09.013",
language = "English",
volume = "308",
pages = "669–682",
journal = "Chemical Engineering Journal",
issn = "1385-8947",

}

TY - JOUR

T1 - A factorial approach to understanding the effect of inner geometry of baffled meso-scale tubes on solids suspension and axial dispersion in continuous, oscillatory liquid-solid plug flows

AU - Ejim, Louisa N.

AU - Yerdelen, Stephanie

AU - McGlone, Thomas

AU - Onyemelukwe, I

AU - Johnston, Blair

AU - Florence, Alastair J.

AU - Reis, Nuno M.

PY - 2017/1/15

Y1 - 2017/1/15

N2 - Oscillatory flow reactors (OFRs) are a new generation of tubular mixing and reaction equipment uniquely capable of combining continuous near plug flow with homogeneous particle suspension, yet the design of OFRs for liquid-solid and multi-phase flow processes relies on rules established during the past two decades from single, liquid-phase studies. A Design of Experiment (DoE) approach was herein implemented for establishing the relationship between four key geometrical parameters of the inner tube baffles and both the suspension of particles and the axial dispersion for liquid-solid continuous flows in 10 mm internal diameter (d) meso-scale tubes with periodic baffles. The parameters evaluated were the orifice open diameter, do = 0.35d–0.50d; the open cross section, α = 0.12d–0.25d, constriction spacing, l = 1.5d–3.0d, and baffle shape (sharp vs smooth edged). A total of ten tubes were tested, five consisting of smooth periodic constrictions (SPC) and the other five of sharp edged periodic constrictions (SEPC) according to a complete 2×2 factorial design with 1 central point. Each tube was experimentally evaluated via optical imaging of suspended monodispersed polyvinyl chloride (PVC) particles. Both SPC and SEPC meso-tubes were capable of delivering a near plug behaviour and the values of axial dispersion coefficient (Dc) estimated for the solids were in the range of 1.0–2.2×10-4 m2 s-1. In contrast, the minimum (critical) fluid oscillation conditions required for full suspension of particles varied significantly, in general with the SPC tubes requiring up to 50% lower amplitude for full particles suspension. Overall, α revealed the dominant parameter in controlling solids backmixing and, and the inner tube geometry requiring the lowest energy input for homogenous particle suspension and minimum Dc (i.e. sharpest residence time distribution) presented a l/d = 3, do = 0.35d, α = 12% and SPC design. This study is believed to support the future design of optimised meso-scale OFR systems for continuous screening and manufacturing of value-added liquid-solid and multi-phase systems, such as catalytic and crystallisation processes.

AB - Oscillatory flow reactors (OFRs) are a new generation of tubular mixing and reaction equipment uniquely capable of combining continuous near plug flow with homogeneous particle suspension, yet the design of OFRs for liquid-solid and multi-phase flow processes relies on rules established during the past two decades from single, liquid-phase studies. A Design of Experiment (DoE) approach was herein implemented for establishing the relationship between four key geometrical parameters of the inner tube baffles and both the suspension of particles and the axial dispersion for liquid-solid continuous flows in 10 mm internal diameter (d) meso-scale tubes with periodic baffles. The parameters evaluated were the orifice open diameter, do = 0.35d–0.50d; the open cross section, α = 0.12d–0.25d, constriction spacing, l = 1.5d–3.0d, and baffle shape (sharp vs smooth edged). A total of ten tubes were tested, five consisting of smooth periodic constrictions (SPC) and the other five of sharp edged periodic constrictions (SEPC) according to a complete 2×2 factorial design with 1 central point. Each tube was experimentally evaluated via optical imaging of suspended monodispersed polyvinyl chloride (PVC) particles. Both SPC and SEPC meso-tubes were capable of delivering a near plug behaviour and the values of axial dispersion coefficient (Dc) estimated for the solids were in the range of 1.0–2.2×10-4 m2 s-1. In contrast, the minimum (critical) fluid oscillation conditions required for full suspension of particles varied significantly, in general with the SPC tubes requiring up to 50% lower amplitude for full particles suspension. Overall, α revealed the dominant parameter in controlling solids backmixing and, and the inner tube geometry requiring the lowest energy input for homogenous particle suspension and minimum Dc (i.e. sharpest residence time distribution) presented a l/d = 3, do = 0.35d, α = 12% and SPC design. This study is believed to support the future design of optimised meso-scale OFR systems for continuous screening and manufacturing of value-added liquid-solid and multi-phase systems, such as catalytic and crystallisation processes.

KW - oscillatory flow

KW - meso-scale reactor

KW - smooth periodic constrictions

KW - design of experiments

KW - solid-liquid flow

KW - plug flow

KW - OFRs

U2 - 10.1016/j.cej.2016.09.013

DO - 10.1016/j.cej.2016.09.013

M3 - Article

VL - 308

SP - 669

EP - 682

JO - Chemical Engineering Journal

T2 - Chemical Engineering Journal

JF - Chemical Engineering Journal

SN - 1385-8947

ER -