CO_2 capture from flue gases using a fluidized bed reactor with limestone

摘要

The CO_2 capture from flue gases by a small fluidized bed reactor was experimentally investigated with limestone. The results showed that CO_2 in flue gases could be captured by limestone with high efficiency, but the CO_2 capture capacity of limestone decayed with the increasing of carbonation/calcination cycles. From a practical point of view, coal may be required to provide the heat for CaCO_3 calcination, resulting in some potential effect on the sor-bent capacity of CO_2 capture. Experiment results indicated that the variation in the capacity of CO_2 capture by using a limestone/coal ash mixture with a cyclic number was qualitatively similar to the variation of the capacity of CO_2 capture using limestone only. Cyclic stability of limestone only undergoing the kinetically controlled stage in the carbonation process had negligible difference with that of the limestone undergoing both the kinetically controlled stage and the product layer diffusion controlled stage. Based on the experimental data, a model for the high-velocity fluidized bed carbonator that consists of a dense bed zone and a riser zone was developed. The model predicted that high CO_2 capture efficiencies (>80%) were achievable for a range of reasonable operating conditions by the high-velocity fluidized bed carbonator in a continuous carbonation and calcination system.