The European CO2 reduction goals can only be achieved with significant improvements in both private and industrial applications and processes. The industrial heat sector plays a substantial role in reaching these climate goals due to the fact that the major part of heat production in Europe comes from fossil energy sources (approx. 75 %). Decarbonization can be boosted, for example, by utilizing renewable energy sources, increasing process efficiency, or utilizing waste heat (approx. 3,000 TWh per year in the European Union). Additionally, the circular economy of valuable resources guarantees a reduction of both primary energy sources and emissions.
The company Seccon GmbH focuses on these points and has developed a patent for using exhaust heat from thermal facilities to process waste materials. The described process uses a hot gas from an industrial production site to pyrolyze the waste in a rotary kiln. The process leads to a separation of the recyclable and valuable materials from unwanted waste fractions. The strategic use of waste heat, which would otherwise be released into the atmosphere, guarantees a positive impact on the CO2 footprint of the industrial plant and a material treatment that is both cost and energy efficient.

The goal of this thesis is to model and analyze the energy flows of an already-constructed pilot plant and of a large-scale rotary kiln, which will be constructed in the next years. In the first part of this thesis the theoretical background of the process is described, the patent of Seccon is summarized, and an overview of the utilized Python libraries is provided.
For the empirical part a Python model (utilizing the OEMOF library) is developed to describe the processing facility and to optimize its energy usage. Multiple constraints are added to take the temperature dependency of the pyrolysis process into consideration. Four scenarios are elaborated to analyze the optimization potential. One of these scenarios depicts the pilot plant, the other three describe the large-scale plant at different time periods and with different process parameters. These input parameters are provided by Seccon, if already verified, and based on literature values.
The objective function of the optimization is the minimization of the total costs, not the minimization of the needed energy amount. Therefore, the energy savings of the optimizations are relatively low (less than 1 %), due to the fact that the energy amount for the pyrolysis is a fixed value that cannot be altered for a given waste mass. Therefore, the optimizer chooses the time dependent material throughflow in such way that the process costs are reduced to a possible minimum. This leads to an increase of the profit in the observed scenarios.
The optimization of the pilot plant leads to an increase in specific profit of approx. 0.025 €/kg. For the large-scale facility, the profit can be increased by approx. 0.002 €/kg if an exhaust gas of a nearby plant is available, and approx. 0.04 €/kg if the entire process energy has to be purchased. These results show that especially for time periods where no hot gas is available, the optimization has a high impact on the generated profits. In addition, the optimizer determines the types of materials, which would lead to economic losses when processed with purchased energy only.