Simulation and multi-objective optimization of an integrated process for hydrogen production from refinery off-gas

Hydrogen production from internal refinery sources such as refinery off-gas (ROG) is one of the most cost-effective solutions to a refinery's hydrogen supply. To maximize the value of such resource, this paper proposes an integrated hydrogen production process based on coupled feed of ROG and natural gas. A rigorous process model is developed and simulated using the commercial process simulator Aspen Plus. To simultaneously maximize hydrogen and steam production, a non-dominated sorting genetic algorithm-II (NSGA-II) is employed to solve the constrained multi-objective optimization problem. A modular framework of the process simulator and multi-objective genetic algorithm is also developed to obtain sets of Pareto-optimal operating conditions, making it easier to optimize the integrated hydrogen production process. The optimization results reveal that the performance of the integrated process can be significantly improved.