Chemical & Process Engineering
Office ACK 7
Room ACK 174a
Address Ackerstraße 76
13355 Berlin

CFD simulations of heat and mass transfer in reactive fixed-bed reactors

Fixed bed catalytic reactors are widely used in the chemical industry. They are used for a variety of applications, such as steam reforming (SRM), dry reforming (DRM) and catalytic partial oxidation of methane (CPOX). The aforementioned processes play an important role in the production of hydrogen and synthesis gas from methane, the latter of which can also be provided from renewable sources and the processes can thus make an important contribution to climate protection.

Heterogeneous catalytic reactions are characterized by a high reaction enthalpy. For the safe and efficient operation of the reactors, it is therefore essential to efficiently remove or introduce heat into the system. Therefore, reactors with small tube diameters are chosen, which are interconnected to form so-called tube bundle reactors. On the other hand, the pressure loss should be kept low, which is why relatively large catalyst particles are used. This leads to reactors with a small tube-to-particle diameter ratio.

The assumption of a homogeneously distributed bed voidage and a fluid dynamic plug-flow profile is no longer justified in this type of reactor, since local wall effects dominate. This significantly effects the energy and mass transfer and thus also the reaction kinetics locally. The design of these reactors with simplified model approaches is problematic, since on the one hand they cannot represent significant effects (e.g. local hot spots) and on the other hand they require knowledge of effective transport parameters (e.g. dispersion coefficient, effective thermal conductivity, effective viscosity). Correlations for the calculation of these parameters are often of limited use and show considerable variations.

Computational Fluid Dynamics (CFD) provides us with a tool to calculate the fluid dynamics as well as the superimposed heat and mass transport in a spatially resolved manner. For this purpose, the complex flow space between the particles is completely resolved and the transport processes are described by numerically solving the Navier-Stokes equations. A coupled description of the heat transport within the particles is also possible. We thus have a tool to perform detailed investigations that would not be feasible experimentally in this flexibility and quality.

Procedure:

A DEM-CFD coupled workflow is used for the numerical simulation. First, a representative randomly packed bed is generated using the Discrete Element Method (DEM). Subsequently, the position and orientation of each particle is extracted and based on these data a CAD description of the bed morphology is generated. For the generation of the computational grid, a special meshing strategy is used, where, depending on the problem, either only the flow space or in addition to it also the particles are meshed.

Objectives:

In addition to the successive extension and experimental validation of the developed method, the simulation results are used to improve the phenomenological understanding of fluid dynamics and transport processes occurring in fixed-bed reactors. With respect to process intensification, new reactor concepts and particle shapes are numerically tested and evaluated with respect to reactor performance. The determination of effective transport parameters, which are necessary for simplified models, is also the focus of my work. The aim is to obtain more reliable results also with simplified models.

Publications

2024

Brandt, V.; Grabowski, J.; Jurtz, N.; Kraume, M.; Kruggel-Emden, H.
DEM and DEM-CFD modeling of systems with geometric constrictions using a new particle location based multi-level coarse graining approach
Powder Technology, 436 :119447
2024
ISSN: 0032-5910
Wu, Mei; Jurtz, Nico; Hohl, Lena; Kraume, Matthias
Multi-objective geometrical optimization of single and dual impeller stirred tanks: An application of the mean age theory approach
Chemical Engineering Research and Design, 203 :709-720
2024
ISSN: 0263-8762
Wu, Mei; Jurtz, Nico; Hohl, Lena; Kraume, Matthias
Multi-impeller mixing performance prediction in stirred tanks using mean age theory approach
AIChE Journal, 70 (1) :e18247
2024

2023

Brandt, V.; Grabowski, J.; Jurtz, N.; Kraume, M.; Kruggel-Emden, H.
A benchmarking study of different DEM coarse graining strategies
Powder Technology, 426 :118629
2023
Grabowski, J.; Jurtz, N.; Brandt, V.; Kraume, M.; Kruggel-Emden, H.
Comparison of sub-grid drag laws for modeling fluidized beds with the coarse grain DEM-CFD approach
Computational Particle Mechanics
2023
Eppinger, Thomas; Jurtz, Nico; Aglave, Ravindra; Kraume, Matthias
Fluidized Bed in Industry Scale: Comparing Eulerian Multiphase and Coarse-grained CFD-DEM Simulation
Chemical Engineering Transactions, 100 :355-360
2023
Junne, Henning; Jurtz, Nico; Schulz, Joschka; Kraume, Matthias; Böhm, Lutz
Rainbow Schlieren Deflectometry for spherical fields: A new algorithm and numerical validation approach
Numerical Heat Transfer, Part B: Fundamentals
2023

2022

Wu, Mei; Jurtz, Nico; Walle, Astrid; Kraume, Matthias
Evaluation and application of efficient CFD-based methods for the multi-objective optimization of stirred tanks
Chemical Engineering Science, 263 :118109
2022
Jurtz, Nico; Schönherr, Tobias David; Kraume, Matthias
Numerical investigation of mechanical axial dispersion in slender fixed-beds
AIChE Journal, 68 (1) :e17431
2022
Jurtz, N.
Particle-resolved CFD as tool for multi-scale design exploration for process intensification in slender fixed-beds
TU Berlin
2022

2021

Eppinger, T.; Jurtz, N.; Kraume, M.
Influence of Macroscopic Wall Structures on the Fluid Flow and Heat Transfer in Fixed Bed Reactors with Small Tube to Particle Diameter Ratio
Processes, 9 (4) :689
2021
ISSN: 2227-9717
Rešetar, I.; Jurtz, N.; Böhm, L.; Kraume, M.; Palz, N.
Integrated Framework for Digital Design and Thermal Analysis of PCM Macro-encapsulations for Passive Indoor Cooling
Sustainable Cities and Society, 66 :102536
2021
ISSN: 2210-6707
Jurtz, N.; Srivastava, U.; Moghaddam, A. A.; Kraume, M.
Particle-Resolved Computational Fluid Dynamics as the Basis for Thermal Process Intensification of Fixed-Bed Reactors on Multiple Scales
Energies, 14 (10)
2021
ISSN: 1996-1073

2020

Jurtz, N.; Wehinger, G.; Srivastava, U.; Henkel, T.; Kraume, M.
Validation of pressure drop prediction and bed generation of fixed-beds with complex particle shapes using discrete element method and computational fluid dynamics
AIChE Journal, 66 (6) :e16967
2020
Jurtz, N.; Flaischlen, S.; Scherf, S.C.; Kraume, M.; Wehinger, G.D.
Enhancing the Thermal Performance of Slender Packed Beds through Internal Heat Fins
Processes, 8 (12) :1528
2020
ISSN: 2227-9717
Jurtz, N.; Kruggel-Emden, H.; Baran, O.; Aglave, R.; Cocco, R.; Kraume, M.
Impact of Contact Scaling and Drag Calculation on the Accuracy of Coarse-Grained Discrete Element Method
Chemical Engineering & Technology, 43 (10) :1959-1970
2020

2019

Jurtz, N.; Kraume, M.; Wehinger, G.
Advances in fixed-bed reactor modeling using particle-resolved computational fluid dynamics (CFD)
Reviews in Chemical Engineering, 35 (2) :139-190
2019
Bornemann, M.; Kern, S.; Jurtz, N.; Thiede, T.; Kraume, M.; Maiwald, M.
Design and Validation of an Additively Manufactured Flow CelltextendashStatic Mixer Combination for Inline NMR Spectroscopy
Industrial and Engineering Chemistry Research, 58 (42) :19562-19570
2019
Röhl, S.; Hohl, L.; Kempin, M.; Enders, F.; Jurtz, N.; Kraume, M.
Influence of Different Silica Nanoparticles on Drop Size Distributions in Agitated Liquid-Liquid Systems
Chemie Ingenieur Technik, 91 (11) :1640-1655
2019
Jurtz, N.; Waldherr, P.; Kraume, M.
Numerical Analysis of the Impact of Particle Friction on Bed Voidage in Fixed-Beds
Chemie Ingenieur Technik, 91 (9) :1260-1266
2019