2010 Volume 36 Issue 1 Pages 41-46
Sulfur oxides (SOx) are one of the main sources of acid rain. In a fluidized bed combustor, limestone is a directly supplied into the combustor, as a desulfurizer in order to decrease the emissions of SOx from fuel, such as sewage sludge and coal. In our previous studies, NaCl-doped limestone has a good performance on the desulfurization characteristics. In the present study, the effect of alkali metal compounds NaCl, KCl and LiCl-dopings on the formation of CaO crystal structure was simulated by the molecular dynamics method. The result indicates that KCl in KCl-doped CaO deforms more largely the CaO crystal structure than NaCl, because K atom tends to separate from Cl atom at high temperature due to larger ionic radius of K than that of Na. For LiCl-doped CaO, LiCl also deforms the CaO crystal structure, because Li, whose ionic radius is smaller than that of Na, can move freely inside the CaO crystal lattice at high temperature. Based on the results obtained by the molecular dynamics simulations, only the NaCl-doping into CaO has a positive effect on the CaO crystallization. Consequently, this NaCl-doping may enhance the desulfurization efficiency. From this viewpoint, the molecular dynamics simulation can well explain the relationship between the desulfurization efficiency of CaO and the effect of alkali metal compounds addition into CaO.
