CFD modeling and control of a steam methane reforming reactor

This work initially focuses on developing a computational fluid dynamics (CFD) model of an industrial scale steam methane reforming reactor (reforming tube) used to produce hydrogen. Subsequently, we design and evaluate three different feedback control schemes to drive the area-weighted average hydrogen mole fraction measured at the reforming tube outlet ((x) over bar (outlet)(H2)) to a desired set-point value ((x) over bar (set)(H2)) under the influence of a tube-side feed disturbance. Specifically, a CFD model of an industrial-scale reforming tube is developed in ANSYS Fluent with realistic geometry characteristics to simulate the transport and chemical reaction phenomena with approximate representation of the catalyst packing. Then, to realize the real-time regulation of the hydrogen production, the manipulated input and controlled output are chosen to be the outer reforming tube wall temperature profile and (x) over bar (outlet)(H2) respectively. On the problem of feedback control, a proportional (P) control scheme, a proportional-integral (PI) control scheme and a control scheme combining dynamic optimization and integral feedback control to generate the outer reforming tube wall temperature profile based on (x) over bar (set)(H2) are designed and integrated into real-time CFD simulation of the reforming tube to track (x) over bar (set)(H2). The CFD simulation results demonstrated that feedback control schemes can drive the value of (x) over bar (outlet)(H2) toward (x) over bar (set)(H2) in the presence of a tube side feed disturbance and can significantly improve the process dynamics compared to the dynamics under open-loop control. (C) 2016 Elsevier Ltd. All rights reserved.