Efficient Hydrogen Production for a Stationary Fuel Cell System: Two-Degree-of-Freedom Control of a Steam Reformer Unit

This article focuses on an essential part of a stationary fuel cell-based power plant, namely the reforming unit that produces H₂. The reformer is fueled by either CH₄ or DME, depending on the catalyst. A detailed dynamic model of the reformer dynamics is derived, which takes into account the spatial distribution of system states such as temperatures and mass fractions. Parameters for the resulting model are identified and a modal transformation is applied to reduce computational complexity and enable comprehensible controller design. The inner loop of the cascaded controller aims at closely following a given H₂ output trajectory. At the same time, the outer control loop keeps the CO output below a given maximum level, thus ensuring that only a minimum of climate relevant gases is exhausted.