SE-SMR process performance in CFB reactors: Simulation of the CO2 adsorption/desorption processes with CaO based sorbents

A 3D numerical model for gas–solid flow was developed and used to study the sorption enhanced steam methane reforming (SE-SMR) and the sorbent regeneration processes with CaO based sorbent in fluidized bed reactors. The SE-SMR process (i.e., SMR and adsorption of CO2) was carried out in a bubbling fluidized bed. The effects of pressure and steam-to-carbon ratio on the reactions are studied. High pressure and low steam-to-carbon ratio will decrease the conversion of methane. But the high pressure makes the adsorption of CO2 faster. The methane conversion and heat utility are enhanced by CO2 adsorption. The produced CO2 in SMR process is adsorbed almost totally in a relative long period of time in the bubbling fluidized bed. It means that the adsorption rate of CO2 is fast enough compared with the SMR rate. The process of sorbent regeneration was carried out in a riser. An unfeasible residence time is required to complete the regeneration process. Higher temperature makes the release of CO2 faster, but the rate is severely restrained by the increased CO2 concentration in gas phase. The temperature distribution is uniform over the whole reactor. Regeneration rate and capacity of sorbents are important factors in selecting the type of reactors for SE-SMR process.