Systematic model‐based design of tolerant chemical reactors

With the raw material and energy transition to biomass‐based feedstocks and renewable energy sources, flexible chemical reactor designs which are capable of converting more than one feedstock will become increasingly important in the chemical industry. In the present work, we refer to chemical reactors which can convert multiple different feedstocks to a desired product with a high and consistent quality as tolerant chemical reactors and propose a systematic model‐based design strategy. The proposed design approach is based on the concept of elementary process functions and the so‐called multilevel reactor design (MLRD) methodology. We use a multiscenario formulation to consider different possible feedstock scenarios and formulate a general multi‐objective dynamic optimization problem that is solved using the direct transcription approach in combination with a scalarization method such as, for example, the normal boundary intersection method or the normalized normal constraint method. The proposed approach is illustrated on the synthesis of maleic anhydride from different n‐butenes and n‐butane feedstocks. The resulting segmented fixed‐bed reactor concept is capable of converting the different feedstocks to maleic anhydride while satisfying additional performance and safety constraints. The results highlight the potential of the proposed design approach.