Simulation of large-scale membrane reformers by a two-dimensional model

The effect of hydrogen removal in membrane reformers is analyzed by a two-dimensional, non-isothermal model. Unlike previous works, which refer to laboratory scale reactors and low space velocity of gas mixture, simulations carried out in the present work concern large-scale reactors (length≃12 mlength≃12 m, diameter≃0.12 mdiameter≃0.12 m) and high hydrogen productivity (volumetric flow rates within 50–130 Nm3/h) involved in industrial applications. Results show that methane conversion is far from unity (about 37–50% dependently on operating conditions), even though larger than that one attainable in absence of membrane (∼28% at simulation conditions). The two-dimensional approach allows the radial distribution of temperature and hydrogen partial pressure to be shown. A lower removal rate of hydrogen than in the one-dimensional model is found due to the lower hydrogen partial pressure near the membrane surface. Finally, thermal level required from membrane reactors is lower than in traditional reformers, so that less demanding ovens and less expensive materials can be used.