CFD modeling and control of a steam methane reforming reactor

• Computational fluid dynamics modeling of steam methane reforming reactor.
• Model calibration and comparison with industrial plant data.
• Integration of computational fluid dynamics modeling and boundary feedback control.
• The use of feedback control improves closed-loop dynamics and feed disturbance rejection.

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¯H2outlet) to a desired set-point value (x¯H2set) 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¯H2outlet 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¯H2set are designed and integrated into real-time CFD simulation of the reforming tube to track x¯H2set. The CFD simulation results demonstrated that feedback control schemes can drive the value of x¯H2outlet toward x¯H2set in the presence of a tube-side feed disturbance and can significantly improve the process dynamics compared to the dynamics under open-loop control.