Abstract
Emissions of SOX from a 4MWth twin-bed pressurized fluidized bed combustor (PFBC) system were measured during long-term (1187 hours) operation. The PFBC consisted of two bubbling beds, A-bed and B-bed. Though both reactors were operated at the same pressure and temperature, emissions of SO2 differed between two reactors. The limestone particles sampled from B-bed, which showed lower emission level, had more internal cracks and their particle size was smaller than those from A-bed. Basic studies of SO2 capture and calcination were also conducted using a pressurized fixed bed reactor for eight kinds of limestone. Calcination of limestone was found to increase reactivity with SO2 under elevated CO2 partial pressure conditions higher than equilibrium partial pressure. Limestones with more internal cracks were found to have higher reactivity towards SO2 absorption. The degree of crystallization measured by X-ray diffraction gave valuable information to predict reactivity and fragmentation. The difference in emission behavior between two fluidized beds is discussed in terms of crack formation and fragmentation.
