A circulating fluidized bed reactor operated in a continuous mode was simulated within two sets of 3D cylindrical coordinates for the downer and riser. The computation of the two reactor units was coupled through the common time step and solid flux. The simulation system was used to study the sorption enhanced steam methane reforming (SE-SMR) and sorbent regeneration simultaneously as carried out in the downer and riser of a circulating fluidized bed reactor. The hydrodynamic behaviors of the downer and the riser were illustrated. The chemical process behavior analysis was compared with that from the simulations operated with the solids in batch mode for the two processes. The similarities and differences of continuous mode and batch mode reactor operations were discussed. It was concluded that high sorbent capacity favors the batch mode operation for the CO2 sorption in the SE-SMR process. In the continuous operation of the SE-SMR and regeneration units, only a small part of sorbent capacity was utilized. (C) 2013 Elsevier Ltd. All rights reserved.