Multi-objective optimization of microchannel reactor for Fischer-Tropsch synthesis using computational fluid dynamics and genetic algorithm

We propose a multi-objective optimization methodology using a stochastic optimization algorithm, a genetic algorithm (GA) with ε-constraint method, and a 2D axisymmetric computational fluid dynamics (CFD)-based Fischer-Tropsch microchannel reactor model, validated by experimental data of CO conversion and CH₄selectivity, for simultaneously maximizing C₅₊productivity and minimizing the temperature rise of a Fischer-Tropsch microchannel reactor. The main mixed integer nonlinear programming (MINLP) optimization problem is decomposed into an external CFD reactor model function and internal optimization constraints. The methodology is applied to the catalyst packing zone division, which is divided and packed with a different dilution ratio to distribute the heat of reaction evenly. The best solutions of the proposed optimizer are reproducible with different crossover fractions and are more efficient than other traditional non-convex constraint local solvers. Based on the Pareto optimal solution of the final optimizer with 4 zones, discrete dilution increases C₅₊productivity to 22% and decreases ΔT_maxto 63.2% compared to the single zone catalyst packing case. Finally, several Pareto optimal solutions and sub-optimal solutions are compared and the results are documented in terms of C₅₊productivity and maximum temperature increase.