Study of limestone calcination with CO2 capture:: Decomposition Behavior in a CO2 atmosphere

In the present work, the effects of temperature (up to 1293 K) and residence time on the decomposition behaviors of limestone particles (0.25 - 0.5 mm) in a CO2 atmosphere were investigated using a continuously operating fluidized bed reactor for CO2 capture. The results show that the rate of limestone decomposition was strongly dependent upon the pressure difference between the equilibrium CO2 pressure and CO2 partial pressure in experiments (P* - P-CO2) with temperature. Decomposition conversions (CaCO3 -> CaO) were 73% at 1193 K and 95% at 1293 K, with a 70 min average residence time of particles in the bed. A model was proposed to describe the distribution of limestone particles in the fluidized bed reactor with residence time. The hydration and carbonation reactivities of CaO produced by the limestone decomposition were also tested. The results show that CaO hydration [CaO to Ca(OH)(2)] can be completed within 11 min; however, the conversion of CaO to CaCO3 in the CaO carbonation test was below 60%.