(400d) In situ Desulfurization Behavior Under Oxy-CFB Boiler Conditions

Owing to the continuously increasing use of high-end technologies, global energy consumption is also growing. In response to the price fluctuation of fossil fuels and stringent environmental regulations, many countries are investing extensively in research efforts to develop environment friendly energy conversion. Among the various technologies, Oxy-CFB(Circulating fluidized bed) boiler is recognized as separation of high purity carbon dioxide and a reduction of NOx emissions. In Oxy-CFB boilers, sulfur dioxide emissions have become major concern. To remove sulfur dioxide emissions in air fired CFB boilers, limestone has generally been used until now. Because operation conditions of oxy-CFB boiler, such as CO2 concentrations and temperature, are quite different from those of conventional air fired CFB boiler. According to the equilibrium of CaCO3 calcination reaction, indirect and direct desulfurization reaction might occur in oxy-CFB boilers. Also, recarbonization reaction could happen in oxy-CFB boilers. Therefore, direct desulfurization and recarbonization reaction of 4 different kinds of limestones(CaCO3 : 72-95wt%) were investigated by using thermogravimetric analyzer under oxy-CFB boiler conditions(CO2 concentration : 60-95%, Temperature : 600-1000℃). Also, reaction models based on the shrinking core model and volumetric model is proposed and evaluated to predict the behavior of limestone in oxy-CFB boilers.