Steam methane reforming (SMR) is recognized as one of the most widely employed processes for producing hydrogen (H₂), effectively converting natural gas (methane) and steam into hydrogen and carbon dioxide at high temperatures. Traditionally, SMR takes place in a plug flow reactor, densely packed with Nickel-based catalyst, and heated through fossil fuel-powered furnaces. To implement cleaner hydrogen production at increased conversions, increasing amount of research is focusing on replacing fossil fuel combustion with electricity, serving as the primary source of heat for the endothermic chemical reactions. With the ultimate objective of comparing novel SMR methods at large scale, we aim to conduct a simulation study with an electrified SMR process. However, for thorough industrial-scale evaluations, a complete process design is imperative, encompassing hydrogen separation from other effluent gases from the SMR. In our study, we have examined pressure swing adsorption (PSA) for the separation unit, renowned in the industry for its efficiency in separating gas mixtures at reduced costs [1]. This process involves employing at least two columns, packed with adsorbent material, activated carbon, to selectively adsorb specific gases within the mixture, consequently separating the targeted (H₂) gas.

More specifically, in this work, we elucidate the optimal operational strategies for industrial-scale electrified steam methane reforming while simultaneously estimating the associated costs and revenue projections. To achieve this goal, we systematically simulate the industrial-scale SMR process between 550-800°C, connecting it with water-gas shift reactors. Subsequently, we determine the precise pressure conditions requisite for attaining 99% purity of hydrogen within the separate effluent gases through pressure swing adsorption simulations utilizing Aspen Adsorption. In our study, we conduct simulations of PSA using hydrogen feeds ranging from 70% to 80% purity and determined the optimal pressure required to achieve a 99% purity of hydrogen as the product. By analyzing different compositions of the hydrogen feed and their corresponding pressure requirements, we performed regression on the data to derive an equation representing the relationship between pressure and composition. Additionally, we utilize this equation to identify the optimal operating point for the entire process simulation.

References:

[1] Song, C., Liu, Q., Ji, N., Kansha, Y. and Tsutsumi, A., 2015. Optimization of steam methane reforming coupled with pressure swing adsorption hydrogen production process by heat integration. Applied energy, 154, pp.392-401.

[2] Zhang, N., Xiao, J., Bénard, P. and Chahine, R., 2019. Single-and double-bed pressure swing adsorption processes for H2/CO syngas separation. International Journal of Hydrogen Energy, 44, pp.26405-26418.

[3] Yang, S.I., Choi, D.Y., Jang, S.C., Kim, S.H. and Choi, D.K., 2008. Hydrogen separation by multi-bed pressure swing adsorption of synthesis gas. Adsorption, 14, pp.583-590.