Particle-scale modeling of the simultaneous carbonation and sulfation in calcium looping for CO2 capture

•Establishment of a particle model for a multi-parallel-reaction process.•Sulfation competes and restrains carbonation in the parallel reactions.•Sulfation is more sensitive to CaO grains and porosity than carbonation. Calcium looping is an effective method to capture CO2 from the flue gas in coal-fired power plants. However, the presence of SO2 in the flue gas will lead to the occurrence of sulfation in the carbonation process. Till now, the reaction pattern of parallel carbonation and sulfation has not yet been investigated at a particle scale, and there is no clear understanding of the individual contributions and interactive behavior in the process. In this work, a particle model is developed by coupling the simultaneous carbonation/sulfation reactions, mass/heat transfer, and geometrical evolution of the sorbent particle. Then, the interaction of two reactions and the effects of reaction conditions and sorbent properties on the process of CO2 capture are investigated. Simulation results show that initial grain size and porosity are the most significant parameters affecting the parallel reactions, which is useful for the high-efficiency utilization of CaO-based sorbents and the operation of the carbonator in calcium looping.