Intensified steam methane reforming coupled with Ca-Ni looping in a dual fluidized bed reactor system: A conceptual design

This study presents an inclusive conceptual design of an intensified steam methane reforming technology coupled with in situ CO2 capture and chemical looping operating in two interconnected fluidized bed reactors. Simulations were run using Aspen Plus (R) and both the hydrodynamic and kinetic phenomena of the reactors were properly implemented through correlations and kinetic models of literature. High-purity H-2 was generated in a bubbling bed reformer, while regeneration occurred at temperatures near 900 degrees C in a fast fluidization reactor due to the generated CO2 that impeded thermodynamically the calcination in lower temperatures. Simulation results had a satisfactory agreement with experiments in a bench-scale fixed bed apparatus, with both being close to equilibrium. A parametric study including the number of stages that the reformer is divided, the NiO/CaO and CaO/C molar ratios and the type of oxidant (O-2/air) of regenerator was conducted. Increasing the NiO/CaO ratio led to lower thermal requirements at the expense of lower H-2 yield and no alteration of the CH4 conversion in contrast to thermodynamics. Air utilization in the regenerator avoided the harsh operational conditions but led to the CO2 isolation with lower purity. It was proposed to reduce the energy requirements by incorporating Ni reoxidation with an oxy-fuel calciner.