Potassium- based carbonate looping in a circulating fluidized bed system including an absorber and a regenerator is a potential CO2 capture technology, which has attracted great focus in recent years. In the current work, the simulation of CO2 capture process is carried out by considering the influence of clusters on the hydrodynamic and reaction, where the multiscale reaction model is employed to reflect the change of CO2 absorption rate caused by clusters. The non- uniform flow structure in the absorber can be predicted very well. The distributions of solid sorbents and temperature field are also predicted. The results reveal that there exists heterogeneous feature for temperature and solid sorbents owing to the cluster formation. The prediction considering the cluster effect is more consistent with experimental data. Meanwhile, the impact of gas inlet velocities on the hydrodynamic and CO2 removal process is evaluated. (C) 2015 Elsevier Ltd. All rights reserved.