CFD Modeling of a Pilot-Scale Steam Methane Reforming Furnace

Abstract

Hydrogen is a required key material for petroleum refineries that convert crude oil into a variety of products with higher economic value, e.g., gasoline. In chemical process plants and petroleum refineries, hydrogen is produced primarily by the steam methane reforming (SMR) process synthesizing hydrogen and carbon oxides from methane and superheated steam in the presence of a nickel-based catalyst network in a steam methane reformer. Traditionally, the optimized and profitable operating conditions of a steam methane reformer are analyzed and determined by on-site parametric study at industrial-scale plants or pilot-scale units, which is an experimental approach, and therefore, it must be conducted by changing process parameters in small increments over a long time period in order to prevent significant production and capital loss. Motivated by the above considerations, the present work focuses on developing a computational fluid dynamics (CFD) model of a pilot-scale steam methane reformer comprised of four industrial-scale reforming reactors, three industrial-scale burners and three flue gas tunnels. The pilot-scale reformer CFD model is developed by analyzing well-established physical phenomena, i.e., the transport of momentum, material and energy, and chemical reactions, i.e., combustion and the SMR process, that take place inside the steam methane reformer. Specifically, the $P-1$ radiation model, standard $k-\epsilon$ turbulence model, compressible ideal gas equation of state and finite rate/eddy dissipation (FR/ED) turbulence-chemistry interaction model are adopted to simulate the macroscopic and microscopic events in the reformer. The conditions for the tube-side feed, burner feed and combustion chamber refractory walls are consistent with typical reformer plant data Latham (2008) so that the simulation results generated by the pilot-scale reformer can be validated by the plant data. The simulation results are shown to be in agreement with publicly available plant data reported in the literature and also with the simulation data generated by a well-developed single reforming tube CFD model. Subsequently, the proposed pilot-scale reformer CFD model is employed for a parametric study of the mass flow rate of the burner feed, i.e., a $20\,\%$ increase from its nominal value. The corresponding simulation results demonstrate the advantages offered by this CFD model for parametric study by showing that with the increased burner feed, the outer reforming tube wall temperature exceeds the maximum allowable temperature; these results were developed quickly with the aid of a CFD model, compared to the timescale on which parametric studies are performed on-site and without the potential for rupture of the reforming tubes during the study.