CFD modeling of radial spreading of flow in trickle-bed reactors due to mechanical and capillary dispersion

Katja Lappalainen (Corresponding Author), Mikko Manninen, Ville Alopaeus

Research output: Contribution to journalArticleScientificpeer-review

55 Citations (Scopus)

Abstract

CFD simulations of trickle-bed reactors are presented with radial spreading of the liquid due to mechanical and capillary dispersion. Simulations are performed with various particle sizes and the significance of the dispersion mechanisms at the industrially relevant particle size range is analyzed. The effect of the bed porosity distribution and particle size to the simulation results is also discussed. The choice of the radial porosity profile is found to have a significant impact to the simulation results, especially when the column to particle diameter ratio, D/dp, is small, in which case the wall flow is important. The dependence of the standard deviation of porosity on the sample size is determined experimentally. Introducing just random variation of porosity to the model is found to describe inadequately the dispersive flow behavior. The presented hydrodynamic model with proper capillary and mechanical dispersion terms succeeds in capturing the features of the two independent physical phenomena. Separate models are presented for each dispersion mechanisms and it is shown that they both can have a significant contribution to the overall dispersion of liquid flowing through a packed bed. The hydrodynamic model is validated against the experimental dispersion profiles from Herskowitz and Smith [1978. Liquid distribution in trickle-bed reactors. A.I.Ch.E Journal 24, 739–454], Boyer et al. [2005. Study of liquid spreading from a point source in trickle-bed via gamma-ray tomography and CFD simulation. Chemical Engineering Science 60, 6279–6288] and Ravindra et al. [1997. Liquid flow texture in trickle-bed reactors: an experimental study. Industrial & Engineering Chemistry Research, 36, 5133–5145]. The extent of liquid dispersion predicted by the presented hydrodynamic model is in excellent agreement with the experiments.
Original languageEnglish
Pages (from-to)207-218
Number of pages12
JournalChemical Engineering Science
Volume64
Issue number2
DOIs
Publication statusPublished - 2009
MoE publication typeA1 Journal article-refereed

Fingerprint

Computational fluid dynamics
Liquids
Porosity
Hydrodynamics
Particle size
Wall flow
Experimental reactors
Packed beds
Chemical engineering
Gamma rays
Tomography
Textures
Experiments

Keywords

  • CFD
  • CFD modeling
  • computational fluid dynamics
  • trickle bed reactors
  • hydrodynamics
  • packed bed
  • liquid dispersion

Cite this

Lappalainen, Katja ; Manninen, Mikko ; Alopaeus, Ville. / CFD modeling of radial spreading of flow in trickle-bed reactors due to mechanical and capillary dispersion. In: Chemical Engineering Science. 2009 ; Vol. 64, No. 2. pp. 207-218.
@article{a2f2112f9711437a8639948b7f487a3a,
title = "CFD modeling of radial spreading of flow in trickle-bed reactors due to mechanical and capillary dispersion",
abstract = "CFD simulations of trickle-bed reactors are presented with radial spreading of the liquid due to mechanical and capillary dispersion. Simulations are performed with various particle sizes and the significance of the dispersion mechanisms at the industrially relevant particle size range is analyzed. The effect of the bed porosity distribution and particle size to the simulation results is also discussed. The choice of the radial porosity profile is found to have a significant impact to the simulation results, especially when the column to particle diameter ratio, D/dp, is small, in which case the wall flow is important. The dependence of the standard deviation of porosity on the sample size is determined experimentally. Introducing just random variation of porosity to the model is found to describe inadequately the dispersive flow behavior. The presented hydrodynamic model with proper capillary and mechanical dispersion terms succeeds in capturing the features of the two independent physical phenomena. Separate models are presented for each dispersion mechanisms and it is shown that they both can have a significant contribution to the overall dispersion of liquid flowing through a packed bed. The hydrodynamic model is validated against the experimental dispersion profiles from Herskowitz and Smith [1978. Liquid distribution in trickle-bed reactors. A.I.Ch.E Journal 24, 739–454], Boyer et al. [2005. Study of liquid spreading from a point source in trickle-bed via gamma-ray tomography and CFD simulation. Chemical Engineering Science 60, 6279–6288] and Ravindra et al. [1997. Liquid flow texture in trickle-bed reactors: an experimental study. Industrial & Engineering Chemistry Research, 36, 5133–5145]. The extent of liquid dispersion predicted by the presented hydrodynamic model is in excellent agreement with the experiments.",
keywords = "CFD, CFD modeling, computational fluid dynamics, trickle bed reactors, hydrodynamics, packed bed, liquid dispersion",
author = "Katja Lappalainen and Mikko Manninen and Ville Alopaeus",
year = "2009",
doi = "10.1016/j.ces.2008.10.009",
language = "English",
volume = "64",
pages = "207--218",
journal = "Chemical Engineering Science",
issn = "0009-2509",
publisher = "Elsevier",
number = "2",

}

CFD modeling of radial spreading of flow in trickle-bed reactors due to mechanical and capillary dispersion. / Lappalainen, Katja (Corresponding Author); Manninen, Mikko; Alopaeus, Ville.

In: Chemical Engineering Science, Vol. 64, No. 2, 2009, p. 207-218.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - CFD modeling of radial spreading of flow in trickle-bed reactors due to mechanical and capillary dispersion

AU - Lappalainen, Katja

AU - Manninen, Mikko

AU - Alopaeus, Ville

PY - 2009

Y1 - 2009

N2 - CFD simulations of trickle-bed reactors are presented with radial spreading of the liquid due to mechanical and capillary dispersion. Simulations are performed with various particle sizes and the significance of the dispersion mechanisms at the industrially relevant particle size range is analyzed. The effect of the bed porosity distribution and particle size to the simulation results is also discussed. The choice of the radial porosity profile is found to have a significant impact to the simulation results, especially when the column to particle diameter ratio, D/dp, is small, in which case the wall flow is important. The dependence of the standard deviation of porosity on the sample size is determined experimentally. Introducing just random variation of porosity to the model is found to describe inadequately the dispersive flow behavior. The presented hydrodynamic model with proper capillary and mechanical dispersion terms succeeds in capturing the features of the two independent physical phenomena. Separate models are presented for each dispersion mechanisms and it is shown that they both can have a significant contribution to the overall dispersion of liquid flowing through a packed bed. The hydrodynamic model is validated against the experimental dispersion profiles from Herskowitz and Smith [1978. Liquid distribution in trickle-bed reactors. A.I.Ch.E Journal 24, 739–454], Boyer et al. [2005. Study of liquid spreading from a point source in trickle-bed via gamma-ray tomography and CFD simulation. Chemical Engineering Science 60, 6279–6288] and Ravindra et al. [1997. Liquid flow texture in trickle-bed reactors: an experimental study. Industrial & Engineering Chemistry Research, 36, 5133–5145]. The extent of liquid dispersion predicted by the presented hydrodynamic model is in excellent agreement with the experiments.

AB - CFD simulations of trickle-bed reactors are presented with radial spreading of the liquid due to mechanical and capillary dispersion. Simulations are performed with various particle sizes and the significance of the dispersion mechanisms at the industrially relevant particle size range is analyzed. The effect of the bed porosity distribution and particle size to the simulation results is also discussed. The choice of the radial porosity profile is found to have a significant impact to the simulation results, especially when the column to particle diameter ratio, D/dp, is small, in which case the wall flow is important. The dependence of the standard deviation of porosity on the sample size is determined experimentally. Introducing just random variation of porosity to the model is found to describe inadequately the dispersive flow behavior. The presented hydrodynamic model with proper capillary and mechanical dispersion terms succeeds in capturing the features of the two independent physical phenomena. Separate models are presented for each dispersion mechanisms and it is shown that they both can have a significant contribution to the overall dispersion of liquid flowing through a packed bed. The hydrodynamic model is validated against the experimental dispersion profiles from Herskowitz and Smith [1978. Liquid distribution in trickle-bed reactors. A.I.Ch.E Journal 24, 739–454], Boyer et al. [2005. Study of liquid spreading from a point source in trickle-bed via gamma-ray tomography and CFD simulation. Chemical Engineering Science 60, 6279–6288] and Ravindra et al. [1997. Liquid flow texture in trickle-bed reactors: an experimental study. Industrial & Engineering Chemistry Research, 36, 5133–5145]. The extent of liquid dispersion predicted by the presented hydrodynamic model is in excellent agreement with the experiments.

KW - CFD

KW - CFD modeling

KW - computational fluid dynamics

KW - trickle bed reactors

KW - hydrodynamics

KW - packed bed

KW - liquid dispersion

U2 - 10.1016/j.ces.2008.10.009

DO - 10.1016/j.ces.2008.10.009

M3 - Article

VL - 64

SP - 207

EP - 218

JO - Chemical Engineering Science

JF - Chemical Engineering Science

SN - 0009-2509

IS - 2

ER -