Presentation made by Olabanji Lawal during the technical research exhibition (TRE) of National Society of Black Engineers (NSBE).

1. Particle-Scale Computational Fluid
Dynamics Modeling of Packed-Bed Reactors
Langsch et al., 2013
Lawal L. Olabanji and Patrick L. Mills
Dept. of Chemical & Natural Gas Engineering
Texas A & M University - Kingsville
Kingsville, TX 78363-8202 USA
Region V Fall Regional Conference National Society of Black Engineers
November 15, 2014

2. Outline
• Packed-Bed Reactors and Computational Fluid Dynamics (CFD)
• CFD Modeling of Packed-Bed Reactors
• Pre-processing
• Code Execution
• Results
• Conclusions
• References

3. • Packed-bed reactors are widely used in petroleum, petrochemical, fine
chemical and pharmaceutical industries [1, 2].
Packed-Bed Reactors and Computational
Fluid Dynamics (CFD)
Liquid hourly space velocity
(LHSV) = 0.2 to 10 hr-1
= 3600 QL[m3/s] / VR [m3]
0.001 < Gm < 2 kg/m2-s
where:
Gm = Gas mass velocity [kg/m2-s]
= USG [m/s] rG [kg/m3]
= QG [m3/s] /AR [m2]) rG [kg/m3]
0.083 < Lm < 25 kg/m2-s
where:
Lm = Liquid mass velocity [kg/m2-s]
= USL [m/s] rL [kg/m3]
= QL [m3/s] /AR [m2]) rL [kg/m3]
• Porous catalyst: 1.6 < dp < 13 mm
• Bed Height: 0.1 < H < 60 m
• Bed diameter 0.01 < dR < 10 m

4. • Computational fluid dynamics (CFD) allows a more detailed
view of the fluid flow and heat transfer mechanisms in
packed-bed reactors, through the resolution of 3-D Reynolds
Averaged Navier-Stokes equations (RANS), together with a
turbulence model.
• The economic impact of improving packed-bed reactors is
quite attractive since the worldwide capacity of materials
processed through trickle-bed reactors is approximately 1.6
billion metric tons/year .
• The mean value of products processed through trickle-bed
reactors is about 300 billion US$/year [1].
Packed-Bed Reactors and Computational
Fluid Dynamics (CFD)

5. Packed-Bed Reactors and Computational
Fluid Dynamics (CFD)
The objectives of this study include:
• Illustrate the use of computational fluid dynamics as a modeling tool for
multiphase packed-bed reactors.
• Numerically solve the mass and momentum transport equations
using a commercial CFD code.
• Obtain the pressure and velocity profiles and compare with
available experimental data from literature.

6. • Governing equations
– The equation of continuity (equation of mass)
– Navier-Stokes Equation (equation of momentum)
– The equation of energy
• Parametric Study, Computers & CFD Codes.
CFD Modeling of Packed-Bed Reactors

7. Bed (Top View) Packing
Structure
4 Layer Bed Section, gap = 1%*Dp Bed (Side
View)
Bed – Isometric View (119,075 Domain
Elements, Coarse Mesh, 200,145
DOF, R=0.25cm, H=1.34cm, N=2)
Pre-processing
Unit Cell in a Simple-Cubic
Packing Arrangement
with about 26,000
Unstructured Tetrahedral
Elements

8. Code Execution
Navier-Stokes Equations
Equation of Continuity
Equation of Energy
Model Equations
Boundary Conditions
Discretization: Finite Elements Method (FEM)
Sparse Matrix Solver: Pardiso (www.pardiso-project.org)

9. Results
Velocity map at y-z plane (m/s) Velocity at z = 20 mm within the cell for Rep = 100
Pressure Contour Map (Pa) Pressure Profile (kPa)

10. • The velocity profile obtained is in good agreement with
experimental results of Suekane et al., 2003 and Gunjal et al.,
2005.
• A CFD methodology has been described to
• to gain insight into interstitial-scale flow in packed-bed
reactors.
• conduct parametric studies with varying particle size and
reactor diameter (Inexpensive as compared to multiple
experimental set-up)
• 3-dimensional numerical simulations for complete beds have high
computational requirements (Random Access Memory).
Conclusions
Future work
• Accounting for temperature effects and then coupling with both
reaction and dispersion.
• Capture the effects of turbulence when flow conditions are
outside laminar flow regime

11. 1. Patrick L. Mills, Milorad P. Dudukovic and Facial Larachi. Multiphase
Reactors – Revisited, Chem. Eng. Sci., 54 (1999) 1975 – 1995.
2. Prashant R. Gunjal, Vivek V. Ranade and Raghunath V. Chaudhari.
Computational Study of a Single-Phase Flow in Packed Beds of Spheres,
AIChE J., Vol 51, No 2, 365-378, 2005.
3. Anthony G. Dixon, Michael Nijemeisland, M.E. Taskin, E.H. Stitt. 3D
CFD Simulations of Steam Reforming with Resolved Intra-particle
Reaction and Gradient. Chem. Eng. Sci., 62 (2007) 4963-4966.
4. Robert Langsch, Anne Mueller, Stefan Haase and Ruediger Lange.
Process Intensification of Gas-Liquid-Solid Reactions in the Production of
Fine Chemicals with Milli Packed Bed Reactors, Catalysis and Reaction
Engineering Division, (26b) AIChE Conference Proceedings 2013.
References

12. Thank you very much