SE-SMR process performance in CFB reactors: Simulation of the CO 2 adsorption/desorption processes with CaO based sorbents

Abstract

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 CO 2) 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 CO 2 faster. The methane conversion and heat utility are enhanced by CO 2 adsorption. The produced CO 2 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 CO 2 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 CO 2 faster, but the rate is severely restrained by the increased CO 2 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.