Physics-Based Dynamic Modeling of Top-Fired Steam Methane Reforming Furnaces Integrating a Simplified Radiation Model

A dynamic, physics-based model has been developed for steam methane reformers (SMRs) with conventional geometries to enable real-time optimization and control, offering a flexible framework adaptable to complex geometries and different operational conditions. Unlike computational fluid dynamics (CFD) models, this approach reduces computation time, making it ideal for online monitoring. The model divides the reformer into zones with uniform temperature and composition, formulating mass, energy, and momentum balances for each zone. Radiative heat transfer is analyzed using the Hottel-zone method with simplified exchange area calculations. Validation against steady-state experimental data confirms the model's accuracy, with minor deviations linked to exchange area calculations. The quantitative assessment yielded a root mean squared error (RMSE) of 0.0156 for the hydrogen mole fraction and 24.84 K for the tube outer wall temperature, calculated with respect to the averaged profiles across cross sections along the furnace height. By solving nonlinear differential-algebraic equations (DAEs) dynamically, the model predicts temperature, composition, and pressure profiles of process and combustion gases, plus tube wall temperature. It captures transient behaviors, with time constants of 46, 40, and 24 min for process gas composition changes, flow reduction, and burner failure, respectively. Dynamic interactions between reformer subsystems are emphasized, as temperature fluctuations in one burner or tube row affect adjacent rows. The model supports dynamic balancing by maintaining safe tube wall temperatures during disturbances, enabling targeted fuel redistribution to reduce temperature nonuniformities, increase allowable operating temperatures, and improve reformer efficiency.