Multi-scale modeling of hydrogen production via steam reforming in a heat-integrated bayonet tube rector

Abstract

The most cost-effective way to produce hydrogen is by steam reforming of methane. Traditionally, conventional fired burners were used for this purpose, despite their drawback of large volumes. The present study modeled an industrial convection reformer integrated into a bayonet tube used for methane steam reforming. The key feature of this compact design is that the furnace and reactor tube remain separate and do not make direct contact with each other. This type of reactor has many complexities from various aspects, including multilayer structure, heat transfer mechanisms, and reactions. A multi-scale one-dimensional model is developed to model the reactor, considering the effects of radiative heat transfer based on fundamental principles. A creative approach is employed to calculate the radiation view factor. A hybrid approach is employed to solve the equations, combining the shooting method with the method of lines to optimize CPU time and ensure equation convergence. The results agree well with plant data across various capacities and operating conditions, achieving 86 % methane conversion while maintaining the fixed bed temperature below 830 °C. Notably, neglecting radiation effects can lead to a 16.2 % error in methane conversion predictions and a 6.5 % error in the estimated reformed gas outlet temperature. Sensitivity analysis reveals that increasing flue temperature from 950 °C to 1300 °C increases methane conversion from 55 % to 95 %, while raising feedstock temperature from 380 °C to 500 °C has a smaller effect, increasing conversion from 83 % to 86 %. These findings highlight the model’s potential for accurately predicting the performance of an industrial-scale convective reformer.