(617hb) Towards Predicting Product Yields in  Steam Methane Reformers Using CFD & Kinetics Co-Simulation Approach

Authors: 
Krishnamoorthy, N., Siemens PLM Software
Frojd, K., CD-adapco
Aglave, R., Siemens PLM Software

Hydrogen produced via Steam Methane Reforming process is a key industrial chemical. Steam Methane Reformers are complex due to the catalytic processes inside tubes coupled with the fireside combustion. Numerical modeling of such systems requires an adequate representation of the physics taking place on the firebox side and on the process side. These processes have been studied individually using simulation in the past. Segregated modeling approaches are limited because one needs to iterate between the models manually. An integrated approach can be computationally prohibitive. In this work, we present a co-simulation approach to model the physics on the firebox side and the process side simultaneously in a computationally feasible way.

The performance of an industrial scale steam-methane reformer unit is studied numerically using the commercial software package STAR-CCM+. In this study, the flow, temperature, and species concentrations on the firebox side are obtained using the steady Reynolds Averaged Navier Stokes (RANS) approach. A species transport based combustion model is used to represent the chemical state space of this system, and the Discrete Ordinates Method (DOM) with the Weighted Sum of Grey Gases (WSGG) property model is used for the radiative transfer calculations on the firebox side. Each of the process tubes in this geometry is represented as 1-D Plug Flow Reactor (PFR), and the relevant flow, energy, and species equations are solved in 1-D (along the axial direction). Since the process tubes in steam-methane reformers are typically packed with catalyst, appropriate models are incorporated in the process side to get the right pressure drop through the packing (Ergun and Hicks correlation), and the right heat transfer coefficient (Leva/Grummer correlation). The coupling between the firebox side and the process side is performed using the co-simulation approach that accounts for the heat transfer between the firebox side and the process side and is implemented in such a way to ensure energy conservation across the boundaries that exchange heat. The model is run for different operating conditions of the system, and the simulation results of temperature and heat flux distributions on the firebox side, CH4 conversion and H2 Yield on the process side are compared with field measurements.