463845 Numerical Investigation on Dispersion Phenomena in Packed Bed Reactors with Low Tube-to-Particle Diameter Ratio

Wednesday, November 16, 2016
Grand Ballroom B (Hilton San Francisco Union Square)
Nico Jurtz1, Gregor D, Wehinger1, Thomas Eppinger2 and Matthias Kraume1, (1)Chair of Chemical and Process Engineering, Technische Universit├Ąt Berlin, D-10587 Berlin, Germany, (2)CD-adapco, Nuremberg, Germany

Numerical investigation on dispersion phenomena in packed bed reactors with low tube-to-particle diameter ratio

Nico Jurtz1, Gregor Wehinger1, Thomas Eppinger2, Matthias Kraume1

1Chair Chemical and Process Engineering, TU Berlin, Berlin, Germany;

2CD-adapco, Nuremberg, Germany;

 

Abstract

Packed bed reactors (PBR) are widely used in the chemical and process industry. They play a key role in the heterogeneous catalysis or in novel process concepts like the chemical looping. A quantity to characterize the mass transfer in PBR’s is the dispersion coefficient. But correlation to determine the dispersion coefficient fail for reactors with a low tube-to-particle diameter ratio due to local wall effects that play an important role (Delgado, 2006).

The flow field of that special reactor configuration can be determined by the use of spatially resolved CFD-simulations using the DEM-CFD coupled approach from (Eppinger, 2011). Based on the calculated flow field a numerical residence time analysis is conducted using the Lagrangian parcel approach. Compared to other passive scalar based approaches this method is beneficial in terms of accuracy and calculation time. The dispersion coefficient can subsequently be calculated based on the simulated residence time distribution function (RTD).

Validation studies show that the presented method allows an accurate and efficient prediction of the RTD. Further simulations show the effect of diameter ratio, Reynolds number and particle shape on the RTD and the dispersion coefficient. Effects like channeling, stagnant zones and back mixing will be detected by analyzing the shape of the RTD and localized by evaluating the calculated flow field.

References

Delgado, J., 2006. A critical review of dispersion in packed beds. Heat Mass Transfer 42, 279-310

Eppinger, T., Seidler, K., Kraume, M., 2011. DEM-CFD simulations of fixed bed reac-tors with small tube to particle diameter ratios. Chem. Eng. J. 166, 324-331.


Extended Abstract: File Not Uploaded