Model-based Design of Optimal Reactors and Processes
Model-based design of optimal reactors and processes
Modern chemical processes pose challenging requirements regarding reactor and process design. Economical and ecological aspects require high energy efficiency and low raw material consumption. To achieve this, a new concept for the design of optimal reactors is necessary, that enables a fundamental understanding of the occurring physical and chemical phenomena and at the same time includes innovative options for process intensification (PI). This is especially true when dealing with complex reaction systems such as multiphase reaction systems and large reaction networks. Additionally, the new concept allows for the consideration and evaluation of novel catalyst supports such as ceramic and metal foam structures. This is the motivation for the research on model-based reactor design methods in the “Catalytic Reactors and Process Technology” group. Special focus is on a novel design methodology within the framework of elementary process functions (EPF), which is continuously further developed and applied.
In the concept of EPF, the chemical process is considered as the route of a fluid element in the thermodynamic state space, where the state of the fluid element can be adjusted by different fluxes. The goal is to adjust the optimal conditions over the complete reaction time, which means to realize the optimal route of the fluid element in the state space. To achieve the best route for a certain objective, different process intensification options can be employed for the manipulation of fluxes. After this, suitable control variables for achieving the desired fluxes are identified and translated into a technical reactor design which can then be evaluated.
The design methodology is based on a rigorous model for the fluid element, consisting of balance equations, thermodynamic relationships and kinetic approaches for transport processes and reactions. The systematic design method is composed of three levels analyzing the influence of possible PI options, of flux constraints and finally of the technical approximation. The resulting dynamic optimization problem is solved using state-of-the-art algorithms and software.

In our group, the reaction kinetics are determined by kinetic modeling, while the realization of the desired transport kinetics is investigated by computer-aided design of catalyst supports. The application of the aforementioned methodology enables the design of innovative tailor-made reactors and processes. The novel reactor components can then be manufactured by, e.g., additive manufacturing techniques (VerTec) using selective electron beam melting. Then, the intensified reactor concept can be validated experimentally, and the experimental results provide valuable feedback for model validation and further developments.
Fundings and Cooperations
Cluster of Excellence “Engineering of Advanced Materials” (EAM)
Helmholtz Energy Alliance “Energy Efficient Multiphase Chemical Processes”
Industry partners
Most Recent Publications
- Kaiser M., Freund H.:
A multimodular pseudoheterogeneous model framework for optimal design of catalytic reactors exemplified by methanol synthesis
In: Chemical Engineering Science 206 (2019), p. 401-423
ISSN: 0009-2509
DOI: 10.1016/j.ces.2019.04.036
- Xie M., Freund H.:
Fast synthesis of optimal chemical reactor networks based on a universal system representation
In: Chemical Engineering and Processing 123 (2018), p. 280-290
ISSN: 0255-2701
DOI: 10.1016/j.cep.2017.11.011
- Maußner J., Freund H.:
Efficient calculation of constraint back-offs for optimization under uncertainty: A case study on maleic anhydride synthesis
In: Chemical Engineering Science 192 (2018), p. 306-317
ISSN: 0009-2509
DOI: 10.1016/j.ces.2018.06.079
- Maußner J., Freund H.:
Optimization under uncertainty in chemical engineering: Comparative evaluation of unscented transformation methods and cubature rules
In: Chemical Engineering Science 183 (2018), p. 329-345
ISSN: 0009-2509
DOI: 10.1016/j.ces.2018.02.002
- Pietschak A., Kaiser M., Freund H.:
Tailored catalyst pellet specification for improved fixed-bed transport characteristics: A shortcut method for the model-based reactor design
In: Chemical Engineering Research & Design 137 (2018), p. 60-74
ISSN: 0263-8762
DOI: 10.1016/j.cherd.2018.06.043
- Xie M., Freund H.:
Optimal reactor design and operation taking catalyst deactivation into account
In: Chemical Engineering Science 175 (2018), p. 405-415
ISSN: 0009-2509
DOI: 10.1016/j.ces.2017.10.010
- Xie M., Freund H.:
Rigorous design of multiphase reactors: Identification of optimal conditions for mass transfer limited reactions
In: Chemical Engineering and Processing 124 (2018), p. 174-185
ISSN: 0255-2701
DOI: 10.1016/j.cep.2017.11.012