Development of a multi-scale mathematical model for green hydrogen production via biogas steam reforming process

Abstract

In this work, a dynamic 2D heterogeneous model for catalytic hydrogen production by biogas steam reforming process was developed, considering both the macroscale and the microscale of the system. The partial differential equations (which describe mass and energy balances) of the mathematical model, have been converted into total differential equations, by spatial discretization and implemented in Matlab/Simulink for process simulation. Based on simulation results, the profiles for mass and concentration of the reactants and products were obtained. The developed model has been validated with available literature data. For the conversion of methane, it predicted 72.43% and for the hydrogen percentage on the dry basis, it gave the value of 72.72%. In this study, a special emphasis was placed on highlighting the influence of a high content of carbon dioxide in biogas on the size of the reactor. The developed model is used to study the effects of step and ramp flow inputs disturbances for the methane conversion and hydrogen percentage on the dry basis and to observe how the reactor design parameters change when the CO2 concentration in the feed flow increases. Furthermore, the developed model for biogas reforming was integrated in a green hydrogen plant with CO2 capture feature for overall performance evaluation (e.g., energy efficiency, CO2 capture rate etc.). The decarbonized green hydrogen plant has promising performance indicators (high overall energy efficiency of 54.5% and a high CO2 capture rate 70%).