In this work, carbonation reaction of CO2 with lime was investigated at both pellet scale and pilot reactor scale. A modified grain model was developed in order to evaluate the kinetic parameters of the reaction. Pellet-scale experiments were carried out in a thermogravimetric analysis (TGA) system providing the data for the model parameters calculation and also confirming the model with experimental data. The activation energy was about 29 kJ/mol for calcined calcium carbonate. Aspen Plus software was used to simulate the packed-bed reactor behavior in order to investigate the accuracy of the kinetic data obtained by the mathematical model.