Modelling of H ₂ production via sorption enhanced steam methane reforming at reduced pressures for small scale applications

The production of H ₂ via sorption enhanced steam reforming (SE-SMR) of CH ₄ using 18 wt % Ni/Al ₂ O ₃ catalyst and CaO as a CO ₂ -sorbent was simulated for an adiabatic packed bed reactor at the reduced pressures typical of small and medium scale gas producers and H ₂ end users. To investigate the behaviour of reactor model along the axial direction, the mass, energy and momentum balance equations were incorporated in the gPROMS modelbuilder ^® . The effect of operating conditions such as temperature, pressure, steam to carbon ration (S/C) and gas mass flow velocity (G _s ) was studied under the low-pressure conditions (2–7 bar). Independent equilibrium based software, chemical equilibrium with application (CEA), was used to compare the simulation results with the equilibrium data. A good agreement was obtained in terms of CH ₄ conversion, H ₂ yield (wt. % of CH ₄ feed), purity of H ₂ and CO ₂ capture for the lowest (G _s ) representing conditions close to equilibrium under a range of operating temperatures pressures, feed steam to carbon ratio. At G _s of 3.5 kg m ⁻² s ⁻¹ , 3 bar, 923 K and S/C of 3, CH ₄ conversion and H ₂ purity were up to 89% and 86% respectively compared to 44% and 63% in the conventional reforming process.