The Ca-Looping (CaL) process is considered as a promising technology for CO2 post-combustion capture in power
generation plants yielding a minor penalty on plant performance as compared with other capture technologies such as conventional amine-based capture systems. This manuscript presents a new carbonator reactor model based on
lab-scale multicyclic CaO conversion results, which take into account realistic CaO regeneration conditions that
necessarily involve calcination under high CO2 partial pressure and high temperature. Under these conditions, CaO
conversion in the diffusion controlled stage is a relevant contribution to the carbonation degree in the typical
residence times. The main novelty of the model proposed in the present work is the consideration of the capture
efficiency in the diffusion controlled phase of carbonation. It is demonstrated that increasing the residence time by
a few minutes in the carbonator yields a significant improvement of the capture efficiency. Model predictions are
shown to agree with experimental results retrieved from pilot-scale tests. The new model allows a more accurate
evaluation and prediction of carbonator’s performance over a wider range of residence times. The results obtained
may be relevant for the optimization of CaL operation parameters to be integrated in real power plants
