(569ey) Addressing the Heat Management Challenge in the Oxidative Coupling of Methane Reactor Using Fixed-Bed, Multi-Zone Optimization with Side Feeding

Oxidative coupling of methane (OCM) is a highly exothermic reaction, so heat management is a pressing concern. Current research is undertaking the OCM innovation from the aspect of reactor design. Side-feeding reactants can improve the performance of OCM by achieving staged, intermediate cooling which helps to maintain a better temperature profile. Researchers have tried to optimize for the best conditions for OCM at the lab scale reactor level, but most of those studies have considered running the reactor isothermally, and not many studies have considered running the reactor adiabatically, which is more practical for OCM during scale-up. Moreover, most studies consider treating the reactor as a single zone and do not consider the effects of side-feeding the reactants across the entire reactor bed. This work uses optimization principles with reactor design to explore a multi-zone reactor framework with efficient feed distribution for OCM. Design decisions in the optimization strategy are considered for feed ratios of each zone inlets, the sizes of each reactor zone, and the intermediate inlet temperatures to each zone. Fixed-bed reactor zones for OCM are modeled as one-dimensional (1-D) and pseudo-homogeneous. The larger reactor zone framework comprises these reactor zone models coupled with mass and energy balances of mixing nodes at each reactor zone inlet. The optimal settings for design decisions are identified using Simulated Annealing (SA). The development of the simulator and the implementation of the SA search scheme will be presented in detail. The maximum number of reactor zones and the optimum design conditions are obtained using the C₂ yield as an objective function. The reactor zone framework will be simulated in both isothermal and adiabatic operations. It is observed that distributing the reactor into multiple zones increases the C₂ yield obtained in both operational modes and, therefore, presents an interesting pathway toward OCM’s scale-up.