Peculiarities of Interactions in the CaCO3/CaO-SO2/SO3-Air System A review

The reactions occurring between CaCO3/CaO and SO2/SO3 in oxidizing atmospheres are discussed. Calcination and sulphation were carried out in a thermobalance under conditions relevant to atmospheric fluidized bed combustion. It is suggested that the quality of limestones as potential SO2 sorbents can be assessed on the basis of tests carried out in a TG apparatus adapted for use with corrosive gases. Limestone calcined under different conditions including the treatment with NaCl leads to changes in surface texture. Sulphated samples were examined in a SEM by energy dispersive X-ray and backscattered electron imaging. Two sulphur-bearing solids (CaSO4 and CaS) were identified. The sulphation rate and extent are determined by the product layer diffusion. The amount of CaS present at the end of the process depends on the particle size of the sorbent. This revised version was published online in July 2006 with corrections to the Cover Date.